Glossary

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Acceptance Testing(also: User Acceptance Testing, UAT, Acceptance Tests)

A form of software testing that validates whether a system meets its specified requirements from the end user's perspective. In accessibility, acceptance tests simulate real user interaction scenarios — such as navigating a web page using only the keyboard or activating…

Accessibility Barrier(also: A11y Barrier)

Any aspect of a digital product, web page, document, or service that prevents or impedes a person with a disability from perceiving, operating, understanding, or using it on an equivalent basis to someone without that disability. Examples include missing alt text on images,…

Accessibility Checker(also: Accessibility Evaluation Tool, Accessibility Scanner, A11y Checker)

An accessibility checker is a software tool that analyzes web content to identify potential barriers for people with disabilities, typically by testing against established guidelines such as WCAG or Section 508. Accessibility checkers range from browser extensions and…

Accessibility Crawler(also: automated accessibility crawler, app crawler for accessibility)

An automated tool that systematically explores an application's user interface—by simulating taps, swipes, and navigation—to discover screens and UI components and then evaluate each against accessibility rules without human involvement. On Android, crawlers typically drive the…

Accessibility Evaluation(also: Accessibility Audit, Accessibility Assessment, Accessibility Review)

The process of assessing whether a digital product, website, or application meets accessibility standards and is usable by people with disabilities. Accessibility evaluation typically combines automated testing tools (which can check technical requirements like image alt text…

Accessibility Evaluation Method(also: AEM, Accessibility Testing Method)

A structured approach or procedure used to assess the accessibility of digital products, websites, or applications. Accessibility evaluation methods include conformance review (checking against standards like WCAG), barrier walkthrough (assessing barriers in context of specific…

Accessibility Heuristics(also: Accessibility Heuristic Evaluation)

A set of broad usability and accessibility principles used to evaluate digital products for barriers that may prevent people with disabilities from using them effectively. Unlike detailed technical checklists such as WCAG success criteria, accessibility heuristics provide…

Accessibility Inspection(also: Accessibility Inspection Method, Accessibility Audit)

An evaluation approach in which an expert or designer reviews an interface against a set of accessibility criteria without recruiting end users, analogous to usability inspection methods such as heuristic evaluation, cognitive walkthrough, or guideline review. Common inspection…

Accessibility Inspector(also: Xcode Accessibility Inspector)

A developer tool included with Apple's Xcode development environment that allows developers and QA testers to audit iOS, macOS, and other Apple platform apps for accessibility issues. The tool can run automated accessibility checks on a connected device or simulator, detecting…

Accessibility Linter(also: A11y Linter, Accessibility Lint)

A static analysis tool that scans source code — typically HTML, CSS, and related web technologies — for accessibility violations against standards such as WCAG. Accessibility linters can be integrated into code editors, build pipelines, or run as standalone tools to flag issues…

Accessibility Metric(also: Web Accessibility Metric, Accessibility Score)

A quantitative measure used to assess and compare the accessibility quality of web pages or websites. Accessibility metrics typically calculate a score (often 0-100%) based on the number and severity of WCAG violations found, weighted by conformance level (Level A weighted…

Accessibility Metric(also: Web Accessibility Metric, Accessibility Quality Metric)

An accessibility metric is a quantitative measure used to assess the level of accessibility compliance of a web page or website. Metrics typically derive from the results of automated or manual evaluation of WCAG checkpoints, aggregating pass/fail/warning outcomes into a single…

Accessibility Monitoring(also: Web Accessibility Monitoring, Accessibility Observatory)

Accessibility monitoring is the ongoing process of tracking and measuring the accessibility level of websites or digital products over time. Because web content is frequently updated, changes can inadvertently introduce new accessibility barriers or degrade previously achieved…

Accessibility Progress Formula(also: APPF, Accessibility Progress Percentage)

A formula for quantitatively tracking progress in addressing accessibility issues on a website, expressed as APPF = A / ((A + B) + (T - C)), where A is the number of applicable checklist items that have been addressed, B is the number not yet addressed, T is the total number of…

Accessibility Repair(also: Automated Accessibility Repair, Accessibility Remediation)

Accessibility repair refers to the process of identifying and fixing accessibility barriers in digital content, ranging from manual remediation by developers to automated tools that can detect and correct certain violations programmatically. Automated repair tools aim to go…

Accessibility Scanner(also: Google Accessibility Scanner, Android Accessibility Scanner)

A testing tool developed by Google that scans Android app screens for common accessibility issues. The scanner checks for problems such as missing content descriptions on interactive elements, insufficient touch target sizes, and low color contrast. It can be run on any Android…

Accessibility overlay(also: Accessibility widget, Accessibility plugin, Overlay tool)

A software layer, typically implemented as a JavaScript widget or browser extension, that applies modifications to a website's presentation or behavior with the goal of improving accessibility. Overlays range from user-driven tools that empower individuals to fix specific…

Automated Accessibility Testing(also: Automated Testing, Accessibility Scanning, A11y Testing)

The use of software tools to programmatically check web content against accessibility guidelines such as WCAG, identifying issues like missing alternative text, insufficient color contrast, empty links, and missing form labels. While automated tools such as WAVE, axe, and…

Automated Evaluation Tool(also: AET, Automated Testing Tool, Accessibility Checker)

Software that automatically scans websites, applications, or documents to detect accessibility violations against standards such as WCAG or Section 508. Common examples include WAVE, axe, AChecker, and Lighthouse. While these tools can efficiently identify many technical…

Barrier Walkthrough(also: BW Method)

The Barrier Walkthrough is a structured expert evaluation method for assessing web accessibility in which evaluators systematically examine a website against a predefined set of accessibility barriers rather than individual guideline success criteria. Unlike conformance-based…

Barrier Walkthrough(also: Structured Walkthrough)

A systematic accessibility evaluation method that guides evaluators through the process of identifying barriers that people with disabilities may encounter on a website. Unlike a standard conformance review that checks against all WCAG success criteria, a barrier walkthrough…

Behaviour-Driven Development(also: BDD, Behavior-Driven Development)

A software development methodology that extends Test-Driven Development by writing test cases as human-readable scenarios in natural language, describing expected system behaviour from the user's perspective. BDD test scenarios typically follow a Given-When-Then format that…

Blackboard Ally(also: Ally)

A commercial accessibility-checking and alternative-format-generation service from Anthology (Blackboard) that integrates with learning management systems such as Blackboard Learn, Canvas, Moodle, and Brightspace. Ally scans uploaded course materials, reports accessibility…

Blurred Vision Simulation(also: Vision Simulation, Low Vision Simulation)

A technique used in accessibility evaluation where evaluators simulate the visual experience of people with reduced visual acuity by artificially blurring their view of a website or application. Methods include using low vision simulation glasses (commercially available from…

Bobby(also: Bobby Worldwide, Watchfire Bobby)

Bobby was one of the earliest and most widely used automated web accessibility testing tools, developed by the Center for Applied Special Technology (CAST) and later acquired by Watchfire (subsequently IBM). Launched in the mid-1990s, Bobby checked web pages against WCAG 1.0…

Brickfield Accessibility Toolkit(also: Brickfield Toolkit)

An accessibility scanning and reporting tool for Moodle developed by Brickfield Education Labs. It is distributed on a freemium model: a community-edition set of scanners is integrated into the Moodle core Accessibility Toolkit, while advanced institutional features (bulk…

Character Error Rate(also: CER)

A metric for evaluating automatic speech recognition (ASR) and optical character recognition (OCR) accuracy, measuring the minimum number of character-level edits (insertions, deletions, substitutions) needed to transform the system output into the reference text, divided by the…

Chartability(also: Chartability Heuristics)

A set of heuristics for assessing the accessibility of data visualizations, developed by Frank Elavsky and the Dataviz Accessibility group. Chartability provides a systematic framework for evaluating whether charts, graphs, maps, and other data visualizations are accessible to…

Checklist Accessibility(also: Checklist Conformism, Checklist Compliance)

A critique of accessibility practice in which organisations treat accessibility as a set of discrete technical checks to be ticked off (alt text present, ARIA labels declared, contrast ratios met) rather than as ongoing engagement with disabled users. Checklist accessibility can…

CogTool

A cognitive modeling tool developed at Carnegie Mellon University that generates quantitative predictions of human task performance times based on the Keystroke-Level Model (KLM) and the ACT-R cognitive architecture. Designers create storyboards of user interface screens and…

Communicability

A quality property of interactive systems proposed by Semiotic Engineering theory, referring to the system's ability to effectively and efficiently convey to users the designer's communicative intentions, logic, and underlying interaction principles. High communicability means…

Conformance Evaluation(also: Conformance Assessment, Accessibility Conformance Testing)

The process of systematically assessing whether a website, application, or digital product meets the requirements of a specific accessibility standard, typically WCAG at a designated conformance level (A, AA, or AAA). Conformance evaluation typically combines automated testing…

Conformance Review(also: WCAG Conformance Review, Conformance Evaluation, Accessibility Conformance Review)

A conformance review is a systematic evaluation of a website or web application against a specific set of accessibility guidelines, most commonly WCAG, to determine whether and to what level the content meets the standard's success criteria. The review process involves checking…

Conformance Testing(also: Compliance Testing, Guideline Review)

An accessibility evaluation method that checks whether a website or digital product meets the requirements specified by accessibility guidelines or standards such as WCAG. Conformance testing can be performed manually by human evaluators or through automated testing tools that…

Correctness(also: Precision, Validity)

In the context of accessibility evaluation, correctness (also called precision) is the proportion of reported accessibility problems that are true problems — that is, issues that genuinely affect users with disabilities rather than false positives. A high correctness rate means…

Disability Simulation(also: Disability Simulator, Empathy Exercise)

A method of accessibility evaluation where non-disabled people experience approximations of the barriers faced by people with disabilities when using technology or navigating environments. In web accessibility, disability simulation tools like IBM's aDesigner visualize how…

EARL(also: Evaluation and Report Language)

A machine-readable format developed by the W3C for expressing the results of accessibility evaluations in a standardized way. EARL uses RDF (Resource Description Framework) to describe test results including the outcome (pass, fail, cannot tell, inapplicable, untested), the test…

Element Detection(also: UI Element Detection, Widget Detection, Object Detection)

The task of automatically identifying the locations and types of user interface components (such as buttons, text fields, images, and checkboxes) from a screenshot using computer vision models. Element detection is important for accessibility because it can identify interactive…

Evaluation Reliability(also: Inter-rater Reliability, Evaluator Agreement)

The extent to which independent accessibility evaluations of the same content produce consistent results. High reliability means that different evaluators using the same method will identify similar sets of accessibility problems, while low reliability indicates that results…

Evaluator Effect

The evaluator effect refers to the phenomenon where different accessibility evaluators identify different sets of problems when assessing the same website, leading to variability in evaluation results. This effect has been documented in both expert reviews and user testing,…

Evaluator Effect

The phenomenon in accessibility and usability evaluation where different evaluators examining the same interface detect different sets of problems and may reach different conclusions about the same issues. The evaluator effect means that no single evaluation can achieve 100%…

F-measure(also: F-score, F1 Score)

A metric that combines correctness (precision) and sensitivity (recall) into a single balanced score, calculated as the harmonic mean of the two values. In accessibility evaluation research, the F-measure provides a single number representing the overall effectiveness of an…

Failure Mode(also: Accessibility failure mode)

In accessibility evaluation, any hindrance caused by a product or web site that prevents a user with a disability from achieving a goal with the same effectiveness, efficiency or safety as a non-disabled user. The term is borrowed from reliability engineering and is used to…

Functiona11ity Error(also: Functionality Error, Functiona11ity)

A term coined by Zhong et al. (2026) — a portmanteau of 'functionality' and 'a11y' (accessibility) — for an accessibility barrier that only manifests through interaction. The static state of the UI appears accessible (elements have labels, sufficient contrast, correct roles),…

Functional Web Accessibility Evaluator(also: FAE, Functional Accessibility Evaluator)

A web accessibility testing tool developed by the University of Illinois that evaluates websites based on coding techniques and best practices rather than simply checking for the presence or absence of specific HTML attributes. Unlike traditional tools that might only verify…

Heuristic Evaluation(also: Expert Review, Heuristic Review)

An accessibility or usability evaluation method in which evaluators examine an interface against a set of recognised principles (heuristics) to identify potential problems. In web accessibility, heuristic evaluation typically involves checking pages against WCAG success criteria…

Heuristic evaluation(also: Expert review, Usability inspection)

A usability and accessibility evaluation method where trained evaluators systematically assess an interface against a set of recognized principles or guidelines (heuristics) to identify potential problems. In accessibility contexts, heuristic evaluation applies principles from…

In Situ Study(also: Field Study, In-the-Wild Study, Remote Study)

An in situ study is a research method where participants are observed or data is collected in their natural environment rather than in a controlled laboratory setting. In accessibility research, in situ studies are particularly valuable because they capture how users interact…

Input Logging(also: Keystroke Logging, Input Event Logging)

The practice of recording detailed timestamped data about keyboard and mouse events — including key presses, releases, mouse movements, clicks, and button states — for analysis of user interaction patterns. In accessibility research, input logging is used to study the…

LLM Agent(also: Generative Agent, Task-Executing Agent)

A software system built around a large language model that autonomously perceives state, plans actions, executes them against an environment (a web page, a mobile app, a shell, a UI), and reflects on outcomes to make progress toward a goal. In accessibility work, LLM agents are…