Glossary

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Brightness Contrast(also: Luminance Contrast, Perceived Brightness Difference)

The difference in perceived brightness between two colors, typically between text and its background. Brightness contrast is a key factor in readability, especially for people with low vision, color vision deficiencies, or those viewing content in challenging lighting…

British Sign Language(also: BSL)

The primary sign language used by deaf communities in the United Kingdom, recognized as an official language under the British Sign Language Act 2022. BSL is distinct from American Sign Language (ASL) and other sign languages, with its own grammar, syntax, and vocabulary. A key…

Broad-Shallow Interface(also: Broad-Shallow UI, Single-Page Interface)

A user interface design pattern that presents a large amount of information on fewer screens, typically requiring scrolling to view all content. Most mainstream apps, including Google Calendar, use this approach. While efficient for experienced users who can quickly scan and…

Broadening Participation in Computing(also: BPC)

A term of art, promoted heavily by the U.S. National Science Foundation and professional societies such as ACM, referring to concerted efforts to increase the participation of groups that are historically underrepresented in computing — including women, people of color, people…

Broca's Aphasia(also: Nonfluent Aphasia, Expressive Aphasia, Motor Aphasia)

A type of aphasia caused by damage to Broca's area in the left frontal lobe of the brain, typically resulting from stroke. People with Broca's aphasia have difficulty producing speech and writing but generally retain good comprehension of spoken and written language. Their…

Browser Accessibility(also: Accessible Browsing, Web Browser Accessibility)

The degree to which web browsers themselves are usable by people with disabilities and age-related impairments, distinct from the accessibility of web content. Browser accessibility encompasses built-in features such as text zoom, high contrast modes, keyboard navigation, screen…

Browser Developer Tools(also: DevTools, Web Inspector, Developer Console)

Built-in browser utilities that allow web developers to inspect, debug, and modify web pages in real-time. Features include DOM inspection, CSS editing, JavaScript debugging, network monitoring, and performance profiling. Major browsers (Chrome, Firefox, Safari, Edge) include…

Browser Extension(also: Browser Plugin, Browser Add-On)

A software module that adds functionality to a web browser, typically installed from a browser's extension store. Browser extensions are a common delivery mechanism for accessibility tools because they can modify webpage content and behavior without requiring changes to the…

Browser Extension Accessibility(also: Accessible Browser Extension, Assistive Browser Extension)

The design and development of web browser extensions that either enhance the accessibility of existing web content or are themselves fully accessible to users of assistive technologies. Assistive browser extensions can augment web pages with additional accessible content,…

Browser Fingerprinting(also: Device Fingerprinting, Canvas Fingerprinting)

A technique used to identify and track users based on the unique characteristics of their web browser and device configuration, including installed plugins, screen resolution, fonts, and accessibility settings. Browser fingerprinting poses privacy concerns for assistive…

Browser Helper Object(also: BHO)

A plugin module for web browsers (originally Internet Explorer) that loads with each browser instance and has access to the Document Object Model and browser events. In accessibility contexts, BHOs have been used to implement client-side web page transformations such as text…

Browsing Fatigue(also: Navigation Fatigue, Screen Reader Fatigue)

Physical and cognitive exhaustion experienced by users — particularly screen reader users and those with motor impairments — when navigating web content through repetitive, effortful interactions. For blind screen reader users, browsing fatigue results from excessive keyboard…

Brushing and Linking(also: Brush and Link, Linked Highlighting)

An interactive visualization technique where selecting or highlighting data in one chart automatically highlights the corresponding data in other linked charts within a dashboard. For example, clicking a bar in a bar chart might highlight the same data points in an adjacent…

Brute-Force Fallback(also: Reset Strategy, Exhaustive Recovery)

A workaround strategy employed by assistive technology users when standard interaction methods fail, involving systematically trying all available options or completely restarting a task from a known good state. Brute-force fallbacks are particularly common among screen reader…

Bubble Cursor(also: Dynamic Cursor, Area Cursor)

An enhanced pointing technique that dynamically resizes the cursor's activation area to make target selection easier, particularly for users with motor impairments. The bubble cursor expands to encompass the nearest target, effectively enlarging the clickable region without…

Bubble Cursor(also: Area Cursor, Enhanced Area Cursor)

An assistive pointing technique where the cursor's activation area is dynamically enlarged to make it easier to select targets on screen. Rather than requiring precise pixel-level accuracy, a bubble cursor expands its clickable region, effectively reducing the precision needed…

Buddy Button

A widely used commercial assistive technology switch manufactured by AbleNet, designed for single-switch access to computers, communication devices, and adapted toys. Buddy Buttons are large, colorful, easy-to-activate mechanical switches that can be positioned on various body…

Bug Report(also: Defect Report, Issue Report)

A structured document submitted to a bug tracking system that describes a software defect, including steps to reproduce, expected behavior, and actual behavior. In the accessibility context, bug reports are a critical mechanism for users with disabilities and developers to…

Bug Repository(also: Bug Tracker, Issue Tracker, Bug Tracking System)

A software system used to record, track, and manage bug reports throughout their lifecycle. Popular examples include Bugzilla, Jira, GitHub Issues, and Monorail (used by Google Chromium). Bug repositories serve as archives of defect information and are valuable for research into…

Built environment

The human-made surroundings that provide the setting for daily activity, encompassing buildings, streets, sidewalks, parks, transit systems, and all other constructed infrastructure. In accessibility, the built environment is a primary source of disabling barriers — missing curb…

Bus stop accessibility(also: Accessible bus stops, Bus stop landmarks)

The design, infrastructure, and information features that make bus stops findable, identifiable, and usable by people with disabilities. For blind and low-vision riders, bus stop accessibility depends heavily on the presence of detectable physical landmarks such as shelters,…

Busyness(also: Activity Level, Activity Intensity)

In the telecare literature, busyness is a coarse-grained measure of overall domestic activity — typically the count of ambient sensor firings per room per time period — used as a proxy for a resident's level of engagement with their home environment, without attempting to…

Bystander privacy(also: Third-party privacy, Incidental privacy)

The privacy concerns of people who are unintentionally captured or observed by technology being used by others. In the context of assistive technology, bystander privacy refers to the rights and concerns of sighted people who may be recorded, analyzed, or described by…