Computer systems

Negative reviews come from problems such as inefficiency, ineffectiveness and high complexity. High satisfaction is a sign of good usability, so it cannot be the cause of complaints.

The alert stops wrong data from being submitted, so the mistake is prevented before it causes a problem. This is error prevention.

Feedback (D) is tempting because a message is shown, but the purpose of checking before submission is to prevent the error.

In moderated testing a moderator is present in real time, watches reactions and asks questions, so verbal feedback is collected during the tasks. Unmoderated and A/B testing have no one to ask questions.

Confidentiality means only authorised people can see sensitive data. Option A is availability, C harms integrity, and D makes no sense because data made for public access is not confidential.

Phishing is a deceptive message pretending to come from a trusted source to steal sensitive information such as login details. Spoofing (faking the sender) may be used inside phishing, but the attack as a whole is phishing.

Encryption turns data into an unreadable form, so even if it is intercepted during transmission it cannot be read without the key. A firewall and access control protect the network and files, not the data on its way.

HCI studies and improves how people interact with computers, making systems more user-friendly, efficient and accessible.

The four elements of HCI are users, tasks, interface and environment. Budget is a project concern, not an element of HCI.

Without alt text, screen readers cannot describe images to blind users, which is an accessibility challenge. Slow load times are a performance issue and poor messages are an error-handling issue.

User-Centred Design puts end users at the centre of design and repeatedly uses their feedback throughout development.

The interface is the point of interaction between the user and the system, such as a GUI, voice commands or gestures.

MFA adds verification steps that make unauthorised access much harder (more security), but the extra steps slow down genuine users (less usability).

The book says encryption can slow data access and processing, and that managing encryption keys can be complex and time-consuming. Key management is the problem that exists only because of encryption, so it is the best answer.

Options A and B are also slowed by encryption, so a teacher may accept them; C is the answer most keys give.

Auto-save and backup let users recover their work after a crash or cyberattack, so tasks do not have to be redone.

Being transparent about how personal data is collected and used is part of privacy (data privacy and user consent). Efficiency and cost are not ethical considerations.

Usability in HCI is the extent to which specific users can use a system to achieve their goals effectively. It has five key components:

• Learnability: how easily new users can do basic tasks the first time, for example with an onboarding tutorial in a banking app.
• Efficiency: how quickly users can do tasks once they have learnt the system, for example shortcut keys in Photoshop.
• Memorability: how easily users remember the system after a gap, for example a yearly tax filing website.
• Error handling: preventing errors and helping users correct and recover from them.
• Satisfaction: how pleasant and comfortable the system is to use.

1. Users: the people who interact with the system; designers study their needs, abilities, limitations, age and skills.
2. Tasks: the specific activities users perform, such as searching, adding to cart and paying on a shopping site.
3. Interface: the point of interaction between user and system (GUI, voice, gestures) through which input and output happen.
4. Environment: the physical and social context of use, such as lighting, noise, space and whether the system is used alone or in a group, for example a kiosk in a busy airport.

Error handling is the system's ability to prevent errors, guide users in correcting them, and help them recover from mistakes. It is a key component of usability because it keeps user trust and makes the interaction smooth even when something goes wrong.

Example: An online airline booking system highlights an invalid date or a blank required field in red and shows a message explaining what to correct, instead of letting the user continue with faulty data. Autofill and suggestions also prevent typing mistakes in names and addresses.

User-Centred Design (UCD) is a design philosophy that puts the end users at the core of the design process. It is an iterative approach: user feedback is collected again and again throughout development and used to improve the design, so the final product matches users' needs, preferences and limitations.

Example: Developers of school software involve teachers and students from the beginning. Testing shows students prefer interactive quizzes to static reading, so quizzes are added, improving engagement and learning.

A password manager stores and autofills strong, unique passwords for different websites (for example LastPass or Bitwarden).

Benefits

• Users do not have to remember many complex passwords, which saves time and effort (efficiency).
• It generates strong, unique passwords for every site, so one stolen password does not open other accounts.
• Autofill fills the password only on the genuine website, which helps protect against fake phishing sites.

Drawbacks

• All passwords are behind one master password; if it is forgotten or stolen, every account is at risk.
• If the password manager company is hacked or its service is unavailable, users may lose access or data may be exposed.

User feedback shows designers how real people actually use the system, which is often different from what designers expect. It contributes in these ways:

• It identifies usability problems such as confusing menus, unclear error messages or slow steps.
• It shows what users like and need, so designers keep useful features and remove unnecessary ones.
• In user-centred design it is collected in every iteration, so each version is closer to user needs.
• It increases user satisfaction and acceptance, because users feel the system was built for them.

Book example: Developers of new educational software involved teachers and students from the beginning. Early testing showed that students preferred interactive quizzes over static reading material. The developers changed the design to include more interactive quizzes, which improved engagement and learning outcomes.

Another example: Early versions of the PayPal app had many features crowded on one screen. Users found it hard to do basic tasks, so the app was simplified over several versions to show the core actions, sending money and checking the balance, on the main screen.

1. Perceivability (alternative ways to receive information): content must be available through more than one sense. For example, give alt text for images so screen readers can describe them to blind users, and captions or transcripts for videos for deaf users.
2. Operability (alternative ways to control the system): every function should work without a mouse, through keyboard navigation, voice commands or other adaptive input devices, so that users with motor impairments can use it.

Other valid considerations are understandability (simple language, clear error messages) and robustness (working with different browsers and assistive technologies).

1. Screen reader support with alt text: all buttons, images and diagrams have text labels so blind or low-vision students can hear the content; also high contrast and zoom options.
2. Captions and transcripts for all video lessons: so deaf or hard-of-hearing students can read the dialogue and sound cues.
3. Keyboard navigation and voice commands: so students with motor impairments can move through lessons and answer quizzes without a mouse.

Together these make the software perceivable and operable for students with visual, hearing and motor impairments.

Accessibility and usability

Accessibility is designing a system so that people with visual, hearing, motor or cognitive impairments can use it. Usability is how effectively, efficiently and satisfactorily users can reach their goals. A system that is not accessible has zero usability for the users it excludes, and often lower usability for everyone else too.

How accessibility challenges reduce usability

• Visual impairments: if images have no alt text, text is small or colours have low contrast, blind and low-vision users cannot perceive the content. Their tasks become ineffective (they cannot finish them) and frustrating.
• Hearing impairments: a video without captions, or an app that gives notifications only by sound, hides information from deaf users.
• Motor impairments: if a system can be used only with a mouse or requires fast, precise touches, users who cannot use a mouse cannot operate it.
• Cognitive impairments: complicated language, cluttered layouts and unclear instructions make the system hard to understand, causing errors.
• Overall effect: users are excluded, make more errors, take longer, feel frustrated and may abandon the product; the organisation also loses customers and may break accessibility laws.

Improvements that address these challenges

Conclusion

Following the POUR principles (perceivable, operable, understandable, robust) removes these barriers. Accessible design improves usability for everyone: captions help people in noisy places, and large buttons help elderly users and anyone in a hurry.

Introduction

HCI is the study of how people interact with computers, with the aim of making systems user-friendly, efficient and accessible. The effectiveness of any interactive system depends on four elements: users, tasks, interface and environment.

1. Users

Users are the people who interact with the system. Designers study their needs, abilities, limitations and preferences, and consider age, cultural background, physical abilities and technical skill. Role: a system designed for its real users fits their skills and goals. Example: a word processor for a professional writer needs strong editing tools, grammar checking, advanced formatting and a distraction-free mode.

2. Tasks

Tasks are the specific activities users need to perform with the system. Role: identifying tasks tells designers which features to provide and how to make each one straightforward, so users reach their goals efficiently. Example: on an e-commerce website the tasks are searching, filtering, reading reviews, adding to the cart and paying; each must be easy.

3. Interface

The interface is the point of interaction between the user and the system, where input is given and output is received. It can be a GUI, voice commands or gestures. Role: a clear, well-organised interface makes the system easy to learn and fast to use. Example: video editing software keeps cut, paste and trim easy to reach, has a precise timeline and lets users customise the workspace.

4. Environment

The environment is the physical context (lighting, noise, available space) and social context (used alone or with others) in which the system is used. Role: the design must suit the conditions of real use. Example: an airport or mall kiosk is used standing, in noise and in a hurry, so it needs large buttons, clear instructions and a screen at a comfortable height.

Conclusion

An effective interactive system results only when all four elements are considered together: the right users doing the right tasks through a suitable interface in their real environment.

Meaning of ethical considerations

Ethical considerations in HCI deal with how technology affects users' rights, privacy and dignity. Ethical design makes sure technology is developed and used in ways that are respectful and fair and that protect users from harm and misuse.

Main ethical considerations

• Data privacy: user data must be collected, stored and used confidentially and only for its intended purpose, and users should control it. Example: Instagram, Facebook, WhatsApp and Twitter collect huge amounts of personal data, so they must protect it strongly and give clear privacy settings.
• User consent: users must be informed and must agree before their data is collected or used; consent must be clear. Example: an app that wants location or contacts should explain why and ask for explicit permission.
• Transparency: users should be told honestly what the system does with their data. Example: Facebook's Privacy Checkup explains step by step who can see posts.
• Fairness and inclusion: systems should not exclude people with disabilities. Example: voice recognition login in online banking for users with physical disabilities.
• Protection from harm: design should avoid manipulating users or encouraging overuse, since excessive social media use is linked with anxiety and depression in young people.

Why these considerations are important

• They protect users' rights and privacy and prevent misuse of personal data such as identity theft.
• They build trust: users keep using systems they believe are honest and safe.
• They help organisations follow laws and regulations, avoiding fines and legal action.
• They protect reputation: data scandals, like the Target breach, cause loss of customers.
• They make technology inclusive and fair, so benefits reach everyone.

Conclusion

An effective system is not enough; it must also be responsible. Ethical HCI makes systems that respect users and society.

Aim

A remote collaboration tool (like a mix of chat, video calls and shared documents) must let team members work together quickly and easily, while keeping company data confidential, accurate and available.

Usability features

• Simple, consistent interface: chat, calls, files and tasks always in the same place, with a clean dashboard (simplicity and consistency).
• Real-time collaboration and auto-save: several people edit a document at once and every change is saved automatically, so no work is lost.
• Clear feedback and notifications: "Saved", "Message delivered", typing indicators and mentions keep everyone informed.
• Onboarding tutorial and search: new members learn quickly (learnability) and find old files and messages fast (efficiency).
• Accessibility: captions in video calls, screen reader support, keyboard shortcuts and dark or high contrast mode.

Security features

• Two-factor authentication and single sign-on: a password plus a code or fingerprint stops attackers who steal passwords.
• End-to-end encryption: messages, calls and files are encrypted in transit and at rest, so intercepted data cannot be read.
• Role-based access control: members see only the projects and files their role needs; admins can remove access when someone leaves.
• Automatic backups and version history: files can be restored after accidental deletion or ransomware (availability and integrity).
• Audit logs and automatic updates: activity is recorded for security audits, and patches install in the background.

Balancing usability and security

To keep security from slowing the team, the tool can remember trusted devices so 2FA is asked only on a new device, use biometric login for speed, give sensible default permissions so users rarely have to request access, and schedule updates outside working hours. In this way the team works efficiently while sensitive data stays protected.

An e-commerce site handles personal details and payments, so it must be secure; it also competes for customers, so it must be easy to use. These three features give both.

1. Secure but quick login and checkout

Use two-factor authentication only when needed (new device or large payment) and allow guest checkout and saved addresses for returning users. Payments go through a trusted payment gateway, so the site never stores full card numbers. Why: attackers who steal a password still cannot log in, while genuine customers finish checkout in a few steps without frustration.

2. HTTPS encryption with visible trust signals

Encrypt all pages with HTTPS (SSL/TLS), and show clear trust signals such as the padlock, the payment partner logos and a confirmation page with an order number. Why: encryption keeps card and address data confidential during transmission, and visible feedback reassures users that their action succeeded and the site is genuine. Encryption on modern servers adds almost no delay, so usability is not reduced.

3. Clear forms with real-time validation and helpful errors

Forms check each field as it is typed ("Please enter a valid email address", "Card number must have 16 digits") and highlight problems in red, with autofill for addresses. Input is also validated on the server. Why: users correct mistakes immediately (error prevention and good feedback), and server-side checks block malicious input such as injection attacks, which improves security.

Supporting features

• Consistent navigation with the search bar and cart always in the same place (like Amazon).
• Strong password rules with a strength meter, so users choose safe passwords without guessing the rules.
• Accessibility: alt text for product images, keyboard navigation and high contrast mode.

These features balance the trade-off: security works mostly in the background, and extra steps appear only when the risk is high.

Meaning of the trade-off

Usability is how easy and intuitive a system is; security is how well it is protected from unauthorised access and attacks. A trade-off exists because adding security usually adds steps, delays or restrictions (less usability), while making a system very easy often removes checks (less security).

1. Authentication complexity

Multi-factor authentication (MFA) adds extra verification, making unauthorised access much harder. But users must enter a code from their phone, which slows access and frustrates them. Real world: a bank login requires a password and then an SMS code; if the phone has no signal, the user cannot log in.

2. Access controls

Restricting permissions makes sure only authorised people can view or change data. But users who often meet "Access denied" must request permission, which slows their work. Real world: an employee waits for IT approval every time a certain file is needed.

3. Encryption

Encryption keeps data unreadable without the key, even if it is intercepted. But it can slow data access and processing, and managing keys is complex. Real world: encrypted patient records are safe, but slow access can be a problem in a hospital emergency; a lost key can make data unrecoverable.

4. Regular updates and patches

Updates fix vulnerabilities and protect against new threats. But they need restarts, interrupt work and can cause compatibility problems. Real world: a Windows update forces a restart during a busy working day.

Other examples

• Automatic screen lock after a short time protects an unattended laptop but annoys a user who is reading.
• Strict password rules (length, symbols, changing every month) lead users to write passwords on paper, which reduces security.

Balancing the trade-off

Designers balance the two by matching security to risk, using convenient methods such as fingerprint login and password managers, asking for extra checks only in unusual situations, giving role-based permissions and scheduling updates outside working hours.

1. Password manager support and biometric login on the mobile app

Allow browsers and password managers to autofill strong passwords, and let app users log in with a fingerprint or face. Why: users no longer type or remember long passwords (usability), yet every account can use a strong, unique password and a biometric factor that cannot be guessed (security).

2. Simple privacy settings and clear consent

Ask for permission clearly before saving cards, sending marketing messages or using location, and give one easy page to change these choices. Why: users stay in control of their data, which follows ethical practice and privacy laws, and a simple settings page is easy to understand for everyone.

3. Auto-save cart, secure backups and fast, protected servers

The shopping cart is saved automatically, data is backed up regularly, and a cloud-based firewall (for example Cloudflare) protects the site from attacks such as denial of service. Why: the site stays available and fast even under attack (availability), and customers never lose their cart or orders (efficiency and good user experience).

Conclusion

Each feature keeps security strong in the background while keeping the customer's steps few and clear, which is the balance a successful e-commerce site needs.

Multi-factor authentication (MFA)

MFA asks the user for two or more kinds of proof: something you know (password), something you have (phone or token) and something you are (fingerprint). It makes unauthorised access much harder, because a stolen password alone is not enough.

Impact of MFA on usability

• Extra steps slow down every login.
• Users are frustrated when the code arrives late or the phone is not with them.
• Losing the phone can lock the user out of the account.
• Less technical users may find the process confusing.

Encryption

Encryption converts data into an unreadable form that only a holder of the decryption key can read. It protects data at rest and in transmission, even if it is intercepted.

Impact of encryption on usability

• Encrypting and decrypting takes processing time, so data access can be slower.
• Managing keys is complex; a lost key can make data permanently unreadable.
• Encrypted systems may be slow when data is urgently needed, for example patient records in an emergency.

How designers can balance these trade-offs

• Adaptive (risk-based) MFA: ask for the second factor only on a new device, new location or high-value transaction, and let users mark trusted devices.
• Convenient factors: use push notifications, fingerprint or face recognition instead of typing codes.
• Backup options: recovery codes or a second phone so users are not locked out.
• Transparent encryption: encrypt automatically in the background (HTTPS, full-disk encryption) with hardware acceleration, so users do not notice it.
• Managed key storage: keys handled by the system or a key management service rather than by the user.
• Clear guidance: simple instructions and helpful messages explain why each step is needed.

With these methods, systems keep strong security while the user experience stays fast and simple.

Consistency means an interface keeps the same design, layout and behaviour across all parts of a system. When buttons, menus and icons look and work the same everywhere, users can predict how the system will behave, and the cognitive load (mental effort) needed to use it is reduced.

Example: Microsoft Word, Excel and PowerPoint use similar ribbons, menus and toolbars, so a user who knows one program moves smoothly to the others. Inconsistent navigation, such as a "Contact Us" button that changes position, confuses users.

Feedback means the system gives clear and immediate responses to user actions, so users know whether their input was successful and what the system is doing in response. Without feedback, users may repeat actions or think the system has frozen.

• Amazon shows a pop-up or visual confirmation when an item is added to the shopping cart.
• A progress bar during software installation shows that work is going on and how much time remains ("About 6 minutes remaining").

Remote usability testing lets users test a system or device from their own location using their own devices. It can be moderated (a moderator watches live through screen sharing) or unmoderated (sessions are recorded).

It is useful because it reaches a wider and more varied audience (different cities or countries), shows how people use the product in their natural environment, and saves the cost of bringing users to a lab. Example: a global software company tests a new feature with users in several countries through screen sharing.

Poor error messages are unclear, overly technical, or give little or no guidance on how to solve the problem. They leave users confused and frustrated, and users may be unable to continue.

They are improved by writing messages that are clear, concise and helpful: explain what went wrong in plain language and give steps to fix it.

Example: "Error 150: Invalid input" is poor. "Please enter the date in the format MM/DD/YYYY" is good because the user knows exactly what to do.

1. Confidentiality: sensitive information is accessible only to authorised users. Example: credit card numbers are encrypted in a database.
2. Integrity: data remains accurate and is not altered or tampered with during storage, transmission or processing, except by authorised people. Example: a digitally signed contract.
3. Availability: systems and data are accessible and usable when needed, even during or after a failure. Example: a backup server takes over when the main server fails.

Together these three principles are called the CIA triad, the foundation of security.

Integrity means data is not changed by unauthorised people. A digital signature is attached to a message or document by the sender. If even one character of the content is changed after signing, the signature no longer matches and becomes invalid.

Example: A user sends a contract by email and digitally signs it. When the receiver finds a valid signature, they can be confident that the content is exactly what the sender wrote and has not been tampered with on the way. A digital signature also shows who sent the document.

1. Data protection policies: rules for handling, storing and transmitting sensitive data, for example encrypting all customer data before sending it.
2. Regular security audits: thorough checks of systems and networks to find vulnerabilities and check compliance, for example quarterly audits.
3. Employee training and awareness: teaching staff about risks such as phishing, because human error causes many breaches.
4. Incident response planning: a ready plan to respond quickly to an attack and minimise damage.

In December 2013 hackers entered Target's network through a third-party vendor using stolen credentials. About 40 million card accounts and personal data of 70 million customers were affected, costing about US$162 million. The lessons are:

• Strengthen cybersecurity, especially for third-party vendors' access.
• Train employees regularly to recognise cyber threats.
• Keep an incident response plan to limit damage.
• Conduct regular audits to find and fix vulnerabilities.

Accessibility is the design of devices, systems and services so that people with a wide range of abilities and disabilities, including visual, hearing, physical and cognitive impairments, can use them.

1. Inclusivity: making technology accessible to the widest possible audience.
2. Adaptability: letting users customise how they interact, for example text size, colours or input method.
3. Compliance: following accessibility standards and legal requirements.

Perceivability: all users must be able to perceive the information and interface, whatever their sensory abilities. Example: alt text for product images lets a screen reader tell a blind user "Red wool sweater with V-neck"; captions let deaf users follow a video.

Operability: all users must be able to navigate and use the interface, whatever their physical or motor abilities. Example: the whole website can be used with only a keyboard, or a smart home can be controlled by voice commands, so users with mobility impairments can turn on lights without touching a switch.

Robustness means content can be interpreted reliably by a wide range of devices, browsers and assistive technologies (such as screen readers), and stays accessible as technology changes.

• Cross-browser compatibility: an educational platform tests its website on Chrome, Firefox, Safari and Edge so all students get the same experience.
• Support for multiple input devices: a computer accepts voice commands, touch gestures, keyboard and mouse, so users who cannot use one method can use another.

1. Closed captions: on-screen text of spoken dialogue, sound effects and other audio cues in videos, as on YouTube.
2. Transcripts: written versions of audio content that users read instead of listening, as provided for TED Talks.
3. Sign language interpretation: an interpreter translates speech into sign language, as in Microsoft Teams calls or the side video on PTV News.

These solutions give the information through visual and text means instead of sound.

Motor impairments make it hard to use a traditional mouse or keyboard. Alternative ways of interacting are provided:

1. Voice recognition software: the user controls the computer and dictates text by voice, for example Dragon NaturallySpeaking.
2. Alternative input devices: adaptive keyboards, adaptive mice and eye-tracking systems that move the pointer with the eyes.
3. On-screen keyboards: a virtual keyboard on the screen used with a mouse, touch screen or other adaptive device.

Memorability is how easily users can remember how to use a system after a period of not using it. A system with high memorability lets users return after weeks or months and perform key tasks without relearning the interface.

It matters most for occasionally used systems. Example: a tax filing website is used once a year. Consistent design patterns, clear labels and a logical flow of steps let the user recall how to fill and submit the forms without starting from zero.

The environment is the physical and social context in which the user interacts with the system. The physical side includes lighting, noise level and available space; the social side is whether the system is used alone or with others. It strongly affects how a system is used.

Example: a public kiosk in an airport or shopping mall is used in a noisy, crowded place by standing people in a hurry. So it needs a simple interface, large buttons, clear instructions and a screen at a comfortable height and angle.

Technology creates new economic opportunities and also challenges such as job disruption.

• Positive: e-commerce platforms like Amazon have created jobs in technology, logistics and customer service, and helped related industries such as digital marketing and online payments grow.
• Negative: robotic automation in factories increases production efficiency but can cause job losses for assembly-line workers.
• Response: training and reskilling programmes help workers move into new jobs.

The environmental implications of technology are its effects through energy consumption, resource use and waste management (especially e-waste). Sustainable practices reduce this ecological footprint.

• Companies such as Google and Microsoft power their data centres with renewable energy to reduce their carbon footprint.
• Manufacturers run take-back programmes and use recyclable materials, such as Apple's recycling programme, so old devices are recycled properly.
• Energy-saving designs such as sleep modes and efficient software also cut power use.

Security side: access controls restrict user permissions so that only authorised people can view or modify information. This protects sensitive data from misuse.

Usability side: when users frequently meet permission errors, they must request access and wait, which slows their work and frustrates them.

Example: an employee needs permission from the IT department again and again to open certain files, which delays tasks. Role-based access, where each role gets the permissions it needs from the start, reduces this problem.

Security: updates and patches fix known vulnerabilities and protect systems against new threats. An unpatched system is an easy target for attackers.

Usability: updates may require system restarts, interrupt users' work and sometimes cause compatibility problems with other software.

Example: frequent software updates force employees to restart their computers at busy times. Scheduling updates outside working hours and letting users postpone restarts keeps security strong with less disruption.

Introduction

Usability is how easily and efficiently users can interact with a system to reach their goals. Six principles guide the design of user-friendly systems.

1. Simplicity

The design should be as straightforward as possible, removing unnecessary complexity and focusing on core functions. Example: the Apple iPod's click-wheel; Google's homepage with only a search box.

2. Consistency

The interface keeps the same design across all parts of the system, so users can predict its behaviour and cognitive load is reduced. Example: similar menus and toolbars in Word, Excel and PowerPoint.

3. Feedback

The system gives clear, immediate responses to user actions, showing whether they succeeded and what is happening. Example: Amazon's "added to cart" confirmation; an installation progress bar.

4. Error prevention

The design prevents errors before they occur and offers easy ways to correct them. Example: Microsoft Word asks "Want to save your changes?" before closing an unsaved file.

5. Learnability

New users should become proficient quickly with minimal training. Example: mobile apps show a tutorial or walkthrough to first-time users.

6. Accessibility

Everyone, including people with disabilities, should be able to use the system comfortably. Example: VoiceOver reads screen text aloud for blind users; TV remotes with large high-contrast buttons for elderly users.

Conclusion

Following these principles produces systems that are effective, efficient and satisfying, the three key aspects of usability.

Usability testing evaluates how user-friendly and effective a system is by observing real users performing tasks. The common types are:

1. Moderated testing

A moderator guides users through tasks, asks questions and observes behaviour in real time, and can clarify instructions or probe issues. Example: participants use a new app in a lab while the moderator watches and asks about their experience.

2. Unmoderated testing

Users complete tasks on their own, often remotely, and sessions are recorded for later analysis. Example: customers at home search for a product and check out while their screens are recorded.

3. Qualitative testing

Focuses on users' experience, thoughts and feelings to gain in-depth insight. Example: interviewing users with open-ended questions about what they liked and disliked.

4. Quantitative testing

Collects numbers such as task time, error rate and success rate to compare versions or set benchmarks. Example: timing users with two navigation menus and counting errors.

5. Remote testing

Users test from their own location on their own devices, moderated or unmoderated. Example: users in several countries test a feature through screen sharing.

6. A/B testing

Two versions are shown randomly to different users and their performance is compared. Example: an online retailer compares sales from two homepage layouts.

Choosing the right method depends on whether the team needs reasons (qualitative, moderated) or measurements (quantitative, A/B), and on where the users are (remote).

Security and the CIA triad

Security is the set of measures that protect information and systems from unauthorised access, use, disclosure, disruption, modification or destruction. It rests on three principles, the CIA triad.

Confidentiality: only authorised people can view or use sensitive data. Example: a company encrypts credit card numbers, so a hacker who enters the database cannot read them without the key.

Integrity: data stays accurate and unaltered during storage, transmission and processing. Example: a digitally signed email contract proves the content has not been changed.

Availability: systems and data are usable when needed, even during failures or attacks. Example: a second server takes over immediately when one server fails.

Security policies and best practices

• Data protection policies: rules for handling, storing and transmitting sensitive data, such as encrypting customer data before transmission.
• Regular security audits: assessments to find vulnerabilities and check compliance, such as quarterly audits.
• Employee training and awareness: reduces human error, a common cause of breaches.
• Incident response planning: a plan to respond quickly and minimise damage.

The Target breach of 2013, caused by stolen vendor credentials, shows why these practices matter.

Accessibility means designing technology so that everyone, including people with disabilities, can use it. Four principles (POUR) guide accessible design.

1. Perceivability

All users must be able to perceive the information and interface components whatever their sensory abilities. Examples: alt text for images, read aloud by screen readers; captions and transcripts for audio and video, such as a captioned YouTube cooking tutorial.

2. Operability

All users must be able to navigate and use the interface whatever their physical or motor abilities. Examples: complete keyboard navigation without a mouse; voice commands to control smart-home lights and thermostat.

3. Understandability

Information and operation must be easy to understand. Examples: the FBR website explains tax filing in simple language; an event registration form highlights required fields and gives real-time instructions to correct mistakes.

4. Robustness

Content must work with a wide range of devices and assistive technologies and remain accessible as technology changes. Examples: a website tested on Chrome, Firefox, Safari and Edge; a computer that accepts voice, touch, keyboard and mouse input.

Conclusion

Together with the key aspects of inclusivity, adaptability and compliance, these principles make sure no user is left behind.

Inclusive technology must understand each type of disability and provide a tailored solution.

1. Visual impairments

Blindness, low vision and colour blindness. Solutions make content perceivable by other means:

• Screen readers (JAWS, NVDA) convert text into speech or braille; they need semantic HTML and ARIA roles.
• High contrast modes in Windows, macOS and websites like BBC.
• Zoom functions in Chrome and Firefox magnify text and images.

2. Hearing impairments

From partial hearing loss to complete deafness. Solutions give information visually or as text:

• Closed captions of dialogue and sound effects, as on YouTube.
• Transcripts of audio content, as for TED Talks.
• Sign language interpretation, as in Microsoft Teams calls and PTV News.

3. Motor impairments

Difficulty using a mouse or keyboard. Solutions give alternative input methods:

• Voice recognition software such as Dragon NaturallySpeaking.
• Alternative input devices: adaptive keyboards, adaptive mice, eye-tracking systems.
• On-screen keyboards controlled by mouse, touch or other adaptive device.

Providing these solutions makes systems usable by everyone and meets accessibility standards.

Cybersecurity measures must balance protection with user experience. Four factors decide whether a solution is effective and sustainable.

1. Efficiency

Protect systems without significantly reducing productivity. Solutions: auto-save and backup (Google Docs saves to Drive in real time); password managers (LastPass, Bitwarden) autofill strong passwords.

2. Cost

Get effective security within budget. Solutions: freemium software (Avast free antivirus); cloud-based security (Cloudflare firewall, no hardware to buy); open source tools (OWASP).

3. Privacy

Handle personal data responsibly. Solutions: private browsing (incognito) on public computers; anonymisation and encryption of patient records; two-factor authentication (password plus phone code).

4. Ethics

Respect user rights and keep trust through transparency and fairness. Solutions: user-friendly privacy settings (Facebook Privacy Checkup); accessible security such as voice recognition login for users with physical disabilities.

A good recommendation considers all four: it is fast to use, affordable, protects privacy and treats every user fairly.

Usability issues frustrate users, cause errors and may make them abandon a product. Four common issues are:

1. Complex interfaces

Too much information, too many options or complicated layouts. Avoid: simplify, prioritise core functions, remove unnecessary features, hide advanced options in menus. Example: PayPal simplified its app to show sending money and checking balance on the main screen.

2. Inconsistent navigation

Menus and buttons change from one section to another, so users feel lost. Avoid: keep navigation uniform on every page, for example a fixed header or footer. Example: Amazon keeps its search bar and menu in the same place.

3. Poor error messages

Unclear or technical messages with no guidance. Avoid: write clear, concise messages in plain language with steps to fix the problem. Example: "Please enter the date in the format MM/DD/YYYY" instead of "Error 150: Invalid input".

4. Lack of accessibility

Users with visual, hearing or motor disabilities are excluded. Avoid: screen reader support, keyboard navigation, alt text and adjustable text size and contrast. Example: Apple's website offers high contrast mode and screen reader support.

Avoiding these issues through usability testing and user feedback leads to effective, efficient and satisfying systems.