Reference
Accessibility Glossary
Plain-language definitions of the terms Shopify merchants encounter when working on accessibility compliance. Every term is linked to the canonical W3C / DOJ / EU primary source.
Alt text (alternative text)
Alt text is a written description of an image that screen readers announce to people who cannot see the image, and that search engines use to understand image content.
WCAG (Web Content Accessibility Guidelines)
WCAG is the international standard for web accessibility, published by the W3C, organized into 50+ testable success criteria across four principles: perceivable, operable, understandable, and robust.
Screen reader
A screen reader is assistive software that converts on-screen content into synthesized speech or refreshable braille, enabling blind and low-vision users to navigate websites, apps, and documents.
ADA (Americans with Disabilities Act)
The ADA is the 1990 US federal civil-rights law prohibiting disability discrimination. DOJ guidance says Title III covers the goods and services that businesses open to the public provide online; business-specific questions can depend on facts and jurisdiction.
EAA (European Accessibility Act)
The EAA (Directive 2019/882) is the European Union law setting functional accessibility requirements for covered products and services, including specified ecommerce services; enforcement began 28 June 2025.
Accessibility overlay
An accessibility overlay is a JavaScript layer that can add user controls or modify the rendered page at runtime. Runtime behavior should not be treated as proof of WCAG, ADA, or EAA compliance.
Accessibility statement
An accessibility statement is a public-facing page describing a website's accessibility approach, assessment scope, known limitations, and a way for users to report barriers.
Color contrast
Color contrast is the luminance ratio between text and its background; WCAG 2.1 AA requires at least 4.5:1 for body text and 3:1 for large text.
Keyboard navigation
Keyboard navigation is the ability to operate every interactive part of a website using only the keyboard — Tab, Shift+Tab, Enter, Space, Arrow keys, and Escape — without requiring a mouse.
Focus indicator
A focus indicator is the visible outline or styling that shows which element currently has keyboard focus, typically a 2-3px outline drawn by the browser.
Compliance score
An automated accessibility score summarizes the results of a defined set of machine-testable checks; it is not a percentage of legal or WCAG conformance.
Section 508
Section 508 is the US federal law requiring electronic and information technology developed, procured, maintained, or used by federal agencies to be accessible to people with disabilities. The Section 508 standards were updated in 2017 to align with WCAG 2.0 AA.
VPAT (Voluntary Product Accessibility Template)
A VPAT is a standardized document, published by the Information Technology Industry Council (ITI), that vendors use to declare a product's conformance with Section 508 / WCAG accessibility standards.
AODA (Accessibility for Ontarians with Disabilities Act)
AODA is Ontario legislation that establishes accessibility standards for covered organizations; its web requirements are implemented through the Integrated Accessibility Standards Regulation and include scoped references to WCAG 2.0 Level AA.
ADA demand letter
An ADA demand letter is a pre-litigation communication alleging disability-access barriers and requesting specified action; its content, deadlines, legal basis, and requested remedies vary by matter.
Serial plaintiff
“Serial plaintiff” is an informal label for a person who files multiple accessibility cases; the label does not determine standing, the merits of an individual claim, or an appropriate response.
ADA Title III
ADA Title III is the section of the Americans with Disabilities Act (42 U.S.C. §§ 12181-12189) that prohibits disability discrimination by covered places of public accommodation; website application can depend on the business, facts, and jurisdiction.
Unruh Civil Rights Act
California's Unruh Civil Rights Act (Civil Code §§ 51-51.3) prohibits business establishments from discriminating against disabled persons and is the state-law vehicle most often paired with ADA Title III claims in California ecommerce-accessibility cases.
Skip link
A skip link is a hidden-by-default link at the top of a page that becomes visible when keyboard-focused, allowing keyboard and screen-reader users to bypass repetitive navigation and jump straight to the main content.
ARIA landmark
ARIA landmarks are HTML5 semantic elements (`<header>`, `<nav>`, `<main>`, `<aside>`, `<footer>`, `<form>`) and their `role=` equivalents that map to navigable page regions for screen-reader users.
Empty alt attribute (`alt=""`)
An empty `alt` attribute (`alt=""`) on an `<img>` element tells assistive technology that the image is purely decorative and should be skipped — distinct from a missing `alt` attribute, which screen readers announce by reading the filename.
WCAG 2.1
WCAG 2.1 is the W3C accessibility standard published in June 2018 that adds 17 success criteria to WCAG 2.0, focused on mobile, low-vision, and cognitive needs; legal use of WCAG varies by jurisdiction and program.
WCAG 2.2
WCAG 2.2 is the W3C accessibility standard published October 2023 that adds 9 success criteria to WCAG 2.1, focused on focus visibility, target size, dragging alternatives, and accessible authentication.
Captions
Captions are time-synchronized text representations of the spoken dialogue, sound effects, and other audio in a video, used by deaf and hard-of-hearing viewers and by anyone watching with sound off.
Transcript
A transcript is the full textual record of an audio or video, including dialogue and significant non-speech audio. Transcripts make audio-only content accessible to deaf users and audio+video content accessible to deafblind users.
Heading hierarchy
Heading hierarchy is the use of `<h1>`–`<h6>` elements to express page and section relationships; levels should represent content structure rather than visual size alone.
Color blindness
Color blindness is a class of visual conditions in which the perception of certain colors is impaired or absent. The most common form, red-green color blindness, affects roughly 8% of men and 0.5% of women of Northern European descent.