Glossary

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Accessible Data Table(also: Accessible Table, Screen Reader-Friendly Table)

A data table designed and implemented to be effectively navigable and comprehensible by screen reader users. Accessible data tables require proper HTML markup including table headers (th elements), scope attributes to associate headers with data cells, captions describing the…

Auditory Graph(also: Audible Graph, Sonified Chart)

A non-visual representation of data that uses sound properties such as pitch, volume, duration, and timbre to convey the values and patterns typically shown in visual charts and graphs. Auditory graphs are an important assistive approach for making data accessible to people who…

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…

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…

Chernoff Faces(also: Chernoff's Faces)

A visualisation technique introduced by Herman Chernoff in 1973 that represents multivariate data by mapping each data variable to a facial feature — eye size, eye spacing, nose length, mouth curvature, face shape, and so on — producing one cartoon face per data sample. The idea…

Choropleth Map(also: Thematic Map, Shaded Map)

A type of thematic map in which geographic areas are shaded or patterned in proportion to a statistical variable, such as population density, income level, or unemployment rate. Darker or more intense colors typically represent higher values. Choropleth maps are widely used by…

Color Adaptive Graphics(also: Colour Adaptive Graphics)

A technique for automatically adjusting the colours in graphical content so that objects maintain similar colour contrast relative to their reference background colours, regardless of the viewing context. Unlike recolouring approaches that focus on preserving the author's…

Composite Figure(also: Multi-panel Figure, Multi-element Figure)

A figure that contains multiple distinct visual elements combined into a single image, such as a series of screenshots labeled (a) through (f), a set of charts showing different data sets, or a mix of photographs and diagrams. Composite figures present a significant…

Content Element(also: Visual Content Element, Non-Text Content)

A visual component within a document that conveys information beyond running text, including tables, charts, images, diagrams, equations, and code blocks. Content elements are often chosen for their ability to communicate complex information concisely and visually, but they…

Coordinated Views(also: Linked Views, Coordinated Multiple Views, Brushing and Linking)

A data visualization technique in which multiple representations of the same dataset are displayed simultaneously and kept synchronized, so that actions in one view (such as selecting, filtering, or sorting) are immediately reflected in all other views. In accessible data…

Cross-Filtering(also: Interactive Filtering, Linked Filtering)

A dashboard interaction technique where applying a filter in one component (such as selecting a category in a chart or using a dropdown widget) automatically updates the data displayed in other related components throughout the dashboard. Cross-filtering enables users to explore…

D3(also: D3.js, Data-Driven Documents)

A JavaScript library for producing dynamic, interactive data visualizations in web browsers using SVG, HTML, and CSS. D3 gives developers fine-grained control over visualization rendering but does not include built-in accessibility features, leaving developers responsible for…

Daltonization(also: Recolouring, Color Remapping)

Daltonization is a computational technique that modifies the colours in an image or on a screen to make them more distinguishable for people with colour vision deficiency (CVD). Named after John Dalton, who first described his own colour blindness in the 18th century,…

Dashboard Accessibility(also: Accessible Dashboards)

The practice of designing data dashboards — visual interfaces combining charts, key performance indicators, filtering widgets, and interactive data querying — so they are usable by people with disabilities, particularly screen reader users. Accessible dashboards require…

Data Comics(also: Visual Data Comics, Narrative Visualization)

An emerging genre of data visualization that presents complex information in a sequential, comic-like format with discrete panels that progressively reveal data and narrative. Data comics break down composite visualizations into smaller, digestible pieces that build upon each…

Data Physicalization(also: Physical Data Visualization)

The practice of representing data through physical, tangible objects rather than on-screen visualizations. Data physicalizations encode information in the shape, texture, size, weight, or other physical properties of objects, making data accessible through touch and spatial…

Data Sonification(also: Auditory Data Display, Sonified Data Visualization)

The systematic mapping of data values to non-speech audio parameters such as pitch, volume, rhythm, timbre, or spatial location to make datasets perceivable through hearing. Data sonification is a key accessibility technique for making charts, graphs, and other data…

Data Visualization(also: Data Viz, Information Visualization)

The graphical representation of data and information using visual elements such as charts, graphs, maps, and diagrams. While data visualization is a powerful tool for communicating patterns and insights, it presents significant accessibility barriers for people with visual…

Data Visualization Accessibility(also: Accessible Data Visualization, Chart Accessibility, Visualization Accessibility)

The practice of designing charts, graphs, diagrams, and other visual data representations so they are perceivable, operable, and understandable by people with disabilities, particularly those who are blind or have low vision. This includes providing meaningful alternative text,…

Data sonification(also: Auditory graph, Audio chart)

The representation of data values through non-speech audio, typically by mapping numerical values to auditory parameters such as pitch, volume, duration, or timbre. Data sonification makes charts and graphs accessible to blind and low-vision users by allowing them to perceive…

Dynamic Tactile Graphics(also: Interactive Tactile Graphics, Animated Tactile Graphics)

Tactile representations of visual information that can change, move, or respond to user interaction in real time, as opposed to traditional static tactile graphics which are fixed once produced. Dynamic tactile graphics can be created through shape displays with movable pins,…

Figure Accessibility(also: Chart Accessibility, Graph Accessibility)

The practice of making visual figures, charts, graphs, and diagrams in documents and publications accessible to people who cannot see them, particularly blind and low vision users. Figure accessibility encompasses multiple approaches including descriptive alt text, data tables,…

Fisheye View(also: Fisheye Lens, Graphical Fisheye)

A focus+context visualization technique, introduced by Furnas, that magnifies a region of interest while progressively compressing surrounding context — analogous to a fisheye camera lens. Used in tree visualizations, menus, and graphs to help users see detail and structure…

Focus+Context(also: Focus plus Context, Focus and Context)

A visualization interaction paradigm that integrates a detailed focus region and its surrounding context into a single unified view, rather than separating them. Techniques include fisheye views, semantic zooming, and lenses that distort or overlay content so users can see fine…

GIS(also: Geographic Information System, Geographic Information Systems)

A class of software systems — such as ArcGIS, QGIS, and open-source geospatial libraries — that capture, store, manipulate, analyze, and visualize geographic and spatial data by linking location coordinates with attribute information. GIS underpins urban planning, public health,…

Geo-referenced Data(also: Geospatial Data, Geographic Data, Georeferenced Data)

Data that is associated with specific geographic locations or regions, such as population statistics by county, crime rates by neighbourhood, or election results by district. Geo-referenced data is typically presented on maps using visual encodings like colour gradients, which…

Geovisualization(also: Geospatial visualization, Geographic visualization)

The use of interactive visual representations — choropleth maps, dot density maps, heat maps, flow maps, and related forms — to make geographic patterns, trends, and spatial relationships visible and explorable. Geovisualizations combine cartographic traditions with…

Gestalt Grouping Principles(also: Gestalt Principles, Gestalt Laws of Perceptual Organization)

A set of principles from perceptual psychology that describe how the human visual system organizes individual elements into coherent groups and patterns. Key principles include spatial proximity (elements near each other are perceived as related), connectedness (elements joined…

Graph(also: Node-Edge Diagram, Network Diagram)

A data structure and visual representation consisting of nodes (vertices) connected by edges (links) that represent relationships between entities. In computer science and mathematics, graphs are used to model networks, hierarchies, flowcharts, and many other relational…

Graph Accessibility(also: Chart Accessibility, Data Visualization Accessibility)

The practice of making charts, graphs, and other data visualisations perceivable and understandable to people with disabilities, particularly those who are blind or have low vision. Graph accessibility encompasses multiple strategies including meaningful alternative text that…

Graphic Accessibility(also: Image Accessibility, Visual Content Accessibility)

The practice of making graphical content — including charts, diagrams, maps, photographs, and illustrations — perceivable and understandable by people who cannot see them. Graphic accessibility encompasses a range of techniques from simple alternative text descriptions to…

Graphicacy(also: Graph Literacy, Visual Literacy)

The ability to read, interpret, and communicate information presented in graphs, charts, maps, and other visual representations of data. Graphicacy is considered a foundational literacy alongside reading, writing, and numeracy. It involves three progressive stages: reading the…

Graphical perception(also: Chart perception, Visual data perception)

The cognitive process by which people extract quantitative information from visual data representations such as charts, graphs, and maps. Graphical perception involves comparing positions, lengths, areas, angles, and colours to make judgements about data values and…

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.…

Health Data Visualization(also: Health Data Display, Patient Data Visualization)

The presentation of personal health information — such as blood glucose levels, blood pressure readings, activity data, or medication schedules — in visual formats including graphs, charts, trend lines, and indicators designed to help patients understand and manage their health…

Heat Map(also: Heatmap, Attention Map, Gaze Map)

A data visualization technique that uses colour intensity to represent the distribution and density of user attention or interaction on a page or interface. In eye tracking research, heat maps aggregate fixation data from multiple users, with warmer colours (red, orange)…

Height-Field Surface(also: Surface plot, Heightfield plot, 2.5D surface)

A type of 3D data visualisation in which a scalar value (for example, elevation, intensity, pressure, or probability) is plotted over a two-dimensional domain, producing a continuous surface that can be rendered as a mesh, contour map, or draped cloth. Height-field surfaces are…

Hypergraph

A mathematical structure that generalises both trees and graphs by allowing edges (called hyperedges) to connect any number of nodes rather than being limited to exactly two. In the context of accessible graphical representations, hypergraphs are used to model the visual…

Information Extraction(also: IE, Data Extraction)

The process of automatically identifying and retrieving structured information from unstructured or semi-structured data sources. In the context of accessibility and data visualization, information extraction refers to how users — particularly screen-reader users — pull specific…

Information Graphics(also: Infographics, Data Graphics, Statistical Graphics)

Visual representations of data, information, or knowledge designed to present complex information quickly and clearly. Common types include bar charts, line graphs, pie charts, scatter plots, and more complex visualizations. Information graphics pose significant accessibility…

Information Perceptualization(also: Perceptualization)

Information perceptualization is the mapping of abstract data or information onto perceptual properties across multiple sensory modalities — vision, hearing, touch, and occasionally taste or smell — in a coordinated, multimodal display. It generalises the more familiar notion of…

Key Performance Indicator(also: KPI)

A quantifiable metric used to evaluate the success of an activity, process, or organization against defined objectives. In dashboards, KPIs are typically displayed as prominent single numbers or summary statistics (e.g., Total Sales, Average Revenue, Customer Count) that provide…

Line Chart Accessibility(also: Accessible Line Graphs, Chart Accessibility)

The practice of making line charts and graphs perceivable and understandable by people with visual impairments through alternative representations such as tactile graphics, sonification, speech descriptions, or multimodal interfaces. Accessible line charts must convey not just…

Line Graph(also: Line Chart, Line Plot)

A type of data visualization that displays information as a series of data points connected by straight line segments, commonly used to show trends over time or relationships between variables. Line graphs are a fundamental tool in mathematics education and data analysis, but…

Mini-VLAT(also: Miniature VLAT)

A 12-item short-form version of the Visualization Literacy Assessment Test developed by Pandey and Ottley that preserves reliability while reducing participant burden. Each chart type from the original VLAT is represented by a single question, making it well-suited for…

Monarch(also: Monarch Tactile Display, Dynamic Tactile Device)

The Monarch is a multi-line refreshable tactile display developed by HumanWare and the American Printing House for the Blind, representing a significant advancement in tactile display technology. Unlike traditional single-line refreshable Braille displays that show only one row…

Multivariate Data(also: Multivariate Dataset, High-Dimensional Data)

Data in which each observation or sample has more than two measured variables (dimensions). Analysing multivariate data is a core task in statistics, science, and business intelligence, but presenting it accessibly is difficult: traditional charts effectively show two or three…

Novint Falcon

A consumer-grade 3D haptic input device originally marketed for gaming that has been widely adopted in accessibility research for providing force feedback to people with visual impairments. The device features a grip attached to three arms that can exert forces in three…

OM Principle(also: Object Model Principle)

A design principle for accessible digital content stating that any digital object is made more accessible by using the application's designated object model for that content rather than visual workarounds. For example, graph titles should be entered in the graphing application's…

Overview+Detail(also: Overview and Detail)

A visualization interaction paradigm that presents a smaller overview view alongside a larger detail view, letting users navigate the whole while inspecting a part. Common in maps, document readers, and data dashboards. For low-vision users, overview+detail can support spatial…