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HAAT Model(also: Human Activity Assistive Technology Model)

A conceptual framework for understanding and designing assistive technology systems that identifies four interconnected components: the human user, the activity being performed, the assistive technology itself, and the context in which the activity takes place. Developed by Cook…

HCI4D(also: Human-Computer Interaction for Development)

A subfield of human-computer interaction that focuses on designing and evaluating interactive technologies specifically for development contexts, addressing the needs of underserved and marginalized communities in low-resource settings. HCI4D research draws on methods from both…

HHS Usability Guidelines(also: Research-Based Web Design and Usability Guidelines, Usability.gov Guidelines)

A comprehensive set of evidence-based web design and usability guidelines published by the U.S. Department of Health and Human Services (HHS). The guidelines cover areas including homepage design, page layout, navigation, scrolling, headings, links, text appearance, content…

HIPAA(also: Health Insurance Portability and Accountability Act)

A 1996 United States federal law that establishes national standards for the protection of certain health information. HIPAA's Privacy Rule governs who may access protected health information (PHI), while its Security Rule mandates administrative, physical, and technical…

HSL(also: Hue Saturation Luminosity, HSL Color Model, HSB)

A colour model that represents colours using three components: Hue (the type of colour, such as red, green, or blue, expressed as a degree on a colour wheel from 0 to 360), Saturation (the purity or intensity of the colour, from grey to fully vivid), and Luminosity or Lightness…

HTML(also: HyperText Markup Language)

The standard markup language used to create and structure content on the World Wide Web. HTML uses elements (tags) to define the semantic structure of documents, including headings, paragraphs, links, lists, tables, forms, and images. Proper use of semantic HTML is fundamental…

HTML Canvas(also: Canvas API, Canvas Element)

An HTML element used to draw graphics on a web page via JavaScript, rendering content as a bitmap image rather than as structured DOM elements. Unlike SVG, canvas content is not inherently accessible to screen readers because it produces a flat pixel surface with no semantic…

HTML Frame(also: Frame, Frameset, IFrame)

An HTML element that divides a web page into multiple independent sections, each displaying a separate document. Framesets (using the frame and frameset elements) split the browser window into distinct panes, while inline frames (iframe) embed one document within another. Frames…

HTML Remediation(also: Accessibility Remediation, A11y Remediation)

The process of modifying HTML code to fix accessibility violations and bring web content into conformance with accessibility guidelines like WCAG. Remediation can involve adding missing attributes (alt text, form labels, ARIA roles), correcting semantic markup (proper heading…

HTML Table(also: Data Table, Web Table)

An HTML table is a structured element in web markup used to organize data into rows and columns. Tables are created using the table, tr (table row), th (table header), and td (table data) elements. For accessibility, data tables must include proper header markup (th elements…

HTML5 Track Element(also: <track> Element, Track Tag, HTML Track)

The HTML5 <track> element is used to specify timed text tracks for <video> and <audio> elements, providing a standardized way to associate captions, subtitles, descriptions, chapters, and metadata with media content. Each <track> element specifies a kind (captions, subtitles,…

HULOP(also: Human-scale Localization Platform)

An open-source indoor navigation platform originally developed by IBM Research to support blind navigation using Bluetooth Low Energy (BLE) beacon fingerprinting for localisation plus a topological map server for route planning and point-of-interest data. HULOP has been used as…

Hackability

A methodology and design philosophy for encouraging DIY assistive technology development in which disabled people, allies, and professionals collaboratively hack, adapt, and remix existing objects into personalized assistive solutions. Hackability events bring together makers…

Hackathon(also: Accessibility Hackathon, Makeathon, ATHack)

A time-limited event (typically hours to days) where participants collaborate intensively to design and build technology solutions, often as prototypes or proofs of concept. Accessibility hackathons specifically focus on creating assistive technologies, but they have been…

Halant(also: Virama, Hasanta)

A diacritical mark used in Indian (Indic) scripts to suppress the inherent vowel of a consonant, enabling the formation of consonant clusters or conjuncts. When a halant follows a consonant, it indicates that the consonant should combine with the following consonant rather than…

Hallucination(also: AI Hallucination, Confabulation)

In the context of AI and large language models, the generation of content that is plausible-sounding but not grounded in the input data or factual reality. Hallucinations pose a particular risk in accessibility applications such as captioning, audio description, or alt text…

HamNoSys(also: Hamburg Notation System)

A phonetic transcription system designed to represent the form of signs in any sign language. Developed at the University of Hamburg, HamNoSys captures detailed information about hand movements, handshapes, and body positioning using a standardised set of symbols. It is one of…

Hamburger Menu(also: Hamburger Icon, Menu Icon)

A UI pattern using three stacked horizontal lines (☰) to hide and reveal a primary navigation menu, most commonly on mobile interfaces. Accessibility considerations include the need for an accessible name (e.g., aria-label="Menu"), keyboard operability, proper focus management…

Hand Tracking(also: Gesture Tracking, Hand Gesture Recognition)

A technology that detects and tracks the position, orientation, and movements of a user's hands and fingers without requiring physical controllers, typically using cameras and computer vision algorithms. In extended reality, hand tracking enables hands-free interaction through…

Hand-Eye Coordination(also: Visual-Motor Coordination, Eye-Hand Coordination)

The ability to coordinate visual information with hand movements to perform tasks such as reaching, grasping, placing, and manipulating objects. For people with low vision, hand-eye coordination can be significantly affected by reduced visual acuity, contrast sensitivity, depth…

Hand-Eye Coordination(also: Visuomotor Coordination, Eye-Hand Coordination)

The ability of the visual system to coordinate information received through the eyes to control and guide hand movements in accomplishing tasks such as writing, catching a ball, or using a touchscreen. Research has shown strong correlations between hand-eye coordination,…

Hand-Object Interaction(also: Hand-Object Interactions, HOI)

The full range of physical actions people perform when grasping, touching, holding, manipulating, or gesturing toward objects with their hands. In accessibility research, hand-object interactions are studied as natural intent cues that can drive assistive technology: for blind…

Hand-Over-Hand Technique(also: Hand-Over-Hand Guidance, Hand-Over-Hand Training)

A training and communication method commonly used with individuals who are blind or have visual impairments, where a trainer places their hands over the learner's hands to physically guide them through the motions of a task. This technique allows the learner to feel the correct…

Hand-Under-Hand Technique(also: Hand-Under-Hand Guidance, Hand-Under-Hand Training)

A training and communication method used with individuals who are blind or have visual impairments, where the learner places their hands on top of the trainer's hands to feel the movements being demonstrated. Unlike hand-over-hand guidance where the trainer controls the…

Handicapping(also: Handicap System, Player Balancing)

A mechanism that asymmetrically adjusts game or contest conditions so competitors of differing ability have more equal chances to win or participate meaningfully. Long established in sports such as golf, horse racing, and archery, handicapping is distinct from matchmaking in…

Hands-Free Control(also: Hands-Free Interaction, Hands-Free Input)

Any method of operating a device or computer system that does not require the use of the hands or fingers. Hands-free control encompasses a range of input techniques including voice commands, eye tracking, head movements, sip-and-puff switches, foot controls, and EMG-based…

Hands-Free Interaction(also: Hands-Free Computing, No-Hands Input, Hands-free)

The ability to operate digital devices and interfaces without using the hands, typically through voice commands, eye tracking, head movements, foot controls, or brain-computer interfaces. Hands-free interaction is critical for users with upper limb motor impairments,…

Hands-Free Interface(also: Hands-Free Computing, Hands-Free Input)

A hands-free interface is a computer interaction system that does not require the use of hands or fingers, enabling users to control software through alternative input channels such as head movements, eye gaze, voice commands, foot pedals, or breath-controlled switches. These…

Handshape(also: Hand Configuration, Handform)

One of the five fundamental parameters of sign language phonology, referring to the specific configuration or shape of the hand(s) when producing a sign. Handshapes are a primary way signs are distinguished from one another and are commonly used as an organizational principle in…

Hapget(also: Haptically-Enhanced Widget)

A hapget (haptically-enhanced widget) is a user interface element that combines a 3D visual representation with haptic (touch) feedback, audio cues, and descriptive metadata to enable non-visual interaction. Introduced in the 3D HapticWebBrowser project, hapgets transform…

Haptic(also: Haptic feedback, Haptic interface)

Relating to the sense of touch as a means of interaction between a user and a device. Haptic interfaces include braille displays that raise and lower pins to represent text, vibration motors in mobile devices that provide tactile feedback, and specialised controllers that offer…

Haptic Communication(also: Social Haptics, Tactile Communication, Haptic Interaction)

A method of conveying information through touch-based signals, vibrations, or physical patterns on the body. Haptic communication is particularly important for individuals with deafblindness or other multisensory impairments, where visual and auditory channels are unavailable or…

Haptic Consent(also: Vibrotactile Consent)

A consent model in which the request for, agreement to, and revocation of consent are communicated through touch or vibration rather than speech. Haptic consent is motivated by accessibility: many neurodivergent people, Deaf and hard-of-hearing people, and people in high-emotion…

Haptic Controller(also: Haptic Interface, Tactile Controller)

An input device that uses touch-based interaction, typically through buttons, pads, or surfaces that can be pressed, tapped, or manipulated. In music technology, haptic controllers include devices like sample pads, drum machines, and synthesizer controllers that respond to…

Haptic Design(also: Vibrotactile Design, Haptic Authoring)

The practice of authoring haptic feedback - typically vibrations, forces, or temperature cues - so that it conveys intended meaning, emotion, or synchronicity with other media. Haptic design involves choosing signal parameters such as amplitude, frequency, timing, and spatial…

Haptic Device(also: Haptic Interface, Force-Feedback Device, Tactile Device)

A hardware device that provides tactile or force feedback to users, enabling them to feel virtual objects, textures, resistance, or vibrations. Haptic devices range from simple vibration motors in smartphones to sophisticated force-feedback systems like the Geomagic Touch…

Haptic Display(also: Tactile Display, Pin-Matrix Display, Refreshable Tactile Display)

A device that conveys information through the sense of touch by dynamically raising and lowering physical elements (typically pins) to create tactile patterns. In accessibility, haptic displays range from single-line refreshable Braille displays used with screen readers to large…

Haptic Experience Model(also: HX Model, HX)

A framework proposed by Kim and Schneider for evaluating user experience with haptic technologies along five perceptual-experiential dimensions: autotelics (the pleasantness of the sensation), realism (fidelity to the depicted phenomenon), harmony (fit with accompanying…

Haptic Exploration(also: Tactile Exploration, Touch Exploration)

The process of acquiring spatial and object information through systematic touch and hand movements. Haptic exploration involves active manipulation and movement across surfaces to perceive shape, size, texture, temperature, and spatial relationships. For people who are blind or…

Haptic Feedback(also: Tactile Feedback, Touch Feedback)

Information conveyed through the sense of touch, typically using vibrations, force, or texture changes to communicate data or system states to a user. In accessibility, haptic feedback provides non-visual, non-auditory confirmation of actions and can convey spatial information,…

Haptic Feedback(also: Tactile Feedback, Haptics)

Technology that communicates information through the sense of touch, using vibrations, pressure, or motion applied to the user's body. In accessibility, haptic feedback provides a non-visual, non-auditory channel for conveying alerts, navigation cues, or interface responses —…

Haptic Field of View(also: Tactile Field of View, Haptic Aperture)

The limited area that can be perceived through touch at any given moment, analogous to the visual field of view but much more restricted. While vision allows perception of an entire scene simultaneously, touch typically provides information only from the area directly under the…

Haptic Glove(also: Data Glove, Tactile Glove, Wearable Haptic Device)

A wearable device worn on the hand that provides tactile feedback through vibration motors, piezoelectric actuators, pin arrays, or other mechanisms embedded in the fingers and palm. In accessibility research, haptic gloves have been explored for several applications: enabling…

Haptic Graph(also: Haptic Chart, Force-feedback Graph)

A haptic graph is a non-visual rendering of a chart or graph — a bar chart, line graph, scatter plot, or mathematical function — that a blind or low-vision user explores by touch, typically through a force-feedback haptic device such as the PHANToM or a vibrotactile tablet.…

Haptic Graphics(also: Dynamic Tactile Graphics, Refreshable Haptic Graphics)

Graphical information presented through the sense of touch, typically on refreshable displays or touchscreen devices. Unlike static tactile graphics (embossed paper or thermoform), haptic graphics can change dynamically and often combine tactile feedback with audio cues. Modern…

Haptic Guiding(also: Force-Based Guiding, Haptic Navigation)

A collaborative interaction technique where one user physically guides another user's cursor or pointer through force feedback, allowing spatial information to be communicated through touch rather than verbal description. In inclusive group work, haptic guiding enables sighted…

Haptic Handle(also: Tactile handle)

A grip on a mobility or guidance device (robot, smart cane, haptic rein, etc.) that conveys information to the user through touch — typically via buttons, vibrotactile feedback, or physical coupling to the device's motion. On suitcase-shaped navigation robots for blind users, a…

Haptic Icon(also: Hapticon)

A short, structured vibrotactile or force pattern designed to carry meaning in the same way a graphical icon or audio earcon does, allowing users to recognize a category of information — an alert, material, identity, or state — through touch alone. The concept generalizes…

Haptic Input(also: Haptic Interaction, Touch Input)

Haptic input refers to interaction methods that use the sense of touch to communicate information between a user and a computer system. This includes devices such as data gloves, force-feedback controllers, and touch-sensitive surfaces that detect hand movements, gestures, and…

Haptic Interface(also: Haptic Device, Tactile Interface, Touch Interface)

An interface that communicates with users through the sense of touch, using vibrations, forces, or textures to convey information. Haptic interfaces can range from simple vibration motors in mobile devices to sophisticated force-feedback controllers and custom tactile displays.…