Accessibility Standards Overview

A practical guide to the core W3C and public-sector frameworks that power inclusive digital experiences: WCAG, ATAG, WAI-ARIA, and Canada’s WET toolkit — plus how WCAG success criteria and conformance levels (A/AA/AAA) map to design, code, and QA.

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WCAG — Web Content Accessibility Guidelines

WCAG defines testable requirements for making web content more accessible to people with disabilities, including blindness/low vision, deafness/hard-of-hearing, motor, speech, cognitive, language, learning, and neurological disabilities. WCAG is technology-agnostic and applies to pages, apps, documents, and media.

WCAG 2.x is organized under four principles (POUR): Perceivable, Operable, Understandable, Robust. Each success criterion is mapped to a level: A (minimum), AA (industry/legal target), AAA (enhanced).

Most public organizations target WCAG 2.1 or 2.2 Level AA. Align your audits, designs, and QA to that level unless a contract or law specifies otherwise.

ATAG — Authoring Tool Accessibility Guidelines

ATAG covers the tools used to create web content (CMSs, WYSIWYG editors, design systems, site builders). It has two parts: A — make the tool itself accessible; B — help authors produce accessible output.

  • Accessible UI, keyboard operability, proper labeling of controls
  • Built-in checkers, templates, and guidance that nudge authors toward WCAG-conformant content
  • Preservation of accessibility data when editing/importing/exporting

WAI-ARIA — Accessible Rich Internet Applications

WAI-ARIA provides roles, states, and properties that expose UI semantics to assistive technologies. Use native HTML first (it has built-in semantics and keyboard support). Add ARIA only when native elements can’t express the needed widget (e.g., a custom tabs, accordion, menu, or dialog).

Common mistakes: using ARIA to replace native controls (role="button" on a <div>), missing keyboard support, forgetting to update aria-expanded/aria-pressed, or trapping focus in modals.

WET — Web Experience Toolkit (Canada)

The Government of Canada’s WET is an open-source UI framework that delivers accessible, bilingual, and responsive patterns compliant with WCAG and GC standards. It provides ready-to-use components (e.g., menus, accordions, carousels, forms, date pickers) that are tested for accessibility and cross-browser compatibility.

  • Standardized templates for GC web properties
  • ARIA-aware widgets with keyboard support
  • Internationalization, performance, and content patterns

WCAG Principles & Success Criteria

PrincipleFocusSample Success Criteria
Perceivable Information can be perceived in multiple ways 1.1.1 Text Alternatives (A), 1.2 Captions (A/AA), 1.4.3 Contrast (AA), 1.4.11 Non-text Contrast (AA)
Operable Interface can be operated via different inputs 2.1 Keyboard (A/AA), 2.4.3 Focus Order (A), 2.4.7 Focus Visible (AA), 2.5 Pointer Gestures/Target Size (2.5.x)
Understandable Content and interactions are predictable and clear 3.2 Predictable (A/AA), 3.3 Input Assistance (A/AA), 3.3.7 Redundant Entry (2.2)
Robust Compatible with user agents & AT 4.1.2 Name, Role, Value (A), 4.1.3 Status Messages (AA)

WCAG Conformance Levels

WCAG conformance is reported at the page level; a site may include pages at different levels during remediation.

LevelMeaningTypical Target
A Addresses the most basic blockers (e.g., missing alt text, no keyboard access). Interim milestone during remediation.
AA Industry/legal target for usability across a wide range of disabilities. Default compliance target for public sector (e.g., ACA, AODA) and many enterprises.
AAA Enhanced accessibility (e.g., extended contrast, sign language for media). Not always feasible site-wide. Applied to specific experiences with critical needs.

Quick Implementation Checklist

  • Design: color contrast ≥ 4.5:1 (text), visible focus, responsive reflow, clear labels & errors.
  • Code: semantic HTML, landmarks, proper headings, form labels, native controls first, ARIA only when needed.
  • Keyboard: Tab order, Enter/Space/Escape patterns, no keyboard traps, logical focus management.
  • Media: alt text, captions, transcripts, audio-only/video-only alternatives.
  • Testing: automated checks + manual review + screen reader (NVDA/JAWS/VoiceOver) + zoom/reflow.
  • Process: add WCAG to DoD, include ATAG-friendly CMS, document conformance & contact.