WCAG Vocabulary | Accessibility Exercises

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The WCAG 2.1 guidelines are organised around four principles — POUR.

What does POUR stand for?

POUR describes the four foundational properties of accessible web content:

Principle	Meaning
Perceivable	Users can sense content with available senses (vision, hearing, touch)
Operable	Can interact regardless of input device (mouse, keyboard, switch)
Understandable	Content and UI behaviour makes sense to users
Robust	Works with current and future assistive technologies

All 78 WCAG 2.1 success criteria map to one of these four principles. Key vocabulary: "WCAG principle", "success criterion", "conformance level (A/AA/AAA)".

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The accessibility audit found a Level AA violation.

What does WCAG Level AA conformance mean?

WCAG defines three conformance levels with increasing strictness:

Level	Criteria count	Legal status
A (minimum)	30 success criteria	Baseline — rarely sufficient alone
AA (standard)	A + 20 additional	Required by EU EAA, Section 508, UK PSBAR
AAA (enhanced)	AA + 28 additional	Not achievable for all content types

Key vocabulary: "conformance level", "Level AA (standard requirement)", "WCAG 2.2 adds 9 new criteria vs. 2.1".

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WCAG Success Criterion 1.4.3 requires a minimum contrast ratio of 4.5:1 for normal text.

What does this criterion address?

SC 1.4.3 Contrast Minimum (Level AA) ensures text is readable by users with low vision and colour vision deficiencies:

Text type	Minimum contrast ratio
Normal text (under 18pt / 14pt bold)	4.5:1
Large text (18pt+ / 14pt+ bold)	3:1
UI components / graphical objects (SC 1.4.11)	3:1

Tools: WebAIM Contrast Checker, Chrome DevTools, axe. Key vocabulary: "contrast ratio", "relative luminance", "large text exception", "1.4.11 Non-Text Contrast".

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A developer argues: "Our users don't use screen readers, so we don't need to worry about accessibility."

Which WCAG principle does this argument misunderstand?

Accessibility serves a far wider group than screen reader users alone:

User group	Accessibility need
Blind / low vision	Screen readers, contrast, zoom
Deaf / hard of hearing	Captions, transcripts, visual alerts
Motor impaired	Keyboard navigation, large targets
Cognitive differences	Plain language, consistent navigation
Situational (bright sun, one hand occupied)	Same accessibility features benefit all

Most users don't disclose disabilities ("invisible disability"). Key vocabulary: "invisible disability", "situational disability", "spectrum of disability".

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The page has a "conformance claim at WCAG 2.1 Level AA."

What is an Accessibility Conformance Report (ACR)?

The ACR / VPAT (Voluntary Product Accessibility Template) is a standard format for communicating product accessibility conformance:

Term	Description
VPAT	US standard template (IT Industry Council); used in procurement
ACR	The completed VPAT document for a specific product
Accessibility Statement (EU)	Required under EU EAA / PSBAR for public sector sites
Self-attestation vs. third-party audit	Procurement teams prefer third-party validation

Key vocabulary: "VPAT", "conformance claim", "procurement evaluation", "self-attestation".