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WCAG

Web Content Accessibility Guidelines (WCAG), is built upon four foundational principles, often referred to by the acronym POUR. These principles provide the overarching goals for accessible web design and development. To meet these principles, WCAG outlines testable success criteria at three levels of conformance: A (the most basic), AA (the mid-range and most commonly adopted), and AAA (the highest and most stringent).

POUR​

P - Perceivable This principle emphasizes that information and user interface components must be presentable to users in ways they can perceive. This means providing alternatives for content that a user might not be able to see or hear.

  • Text Alternatives: Providing text descriptions for non-text content like images and videos.

  • Time-Based Media: Offering captions for videos and transcripts for audio content.

  • Adaptable: Ensuring content can be presented in different ways, such as with a simplified layout, without losing information or structure.

  • Distinguishable: Making it easier for users to see and hear content, including separating foreground from background. This involves considerations like color contrast.

O - Operable This principle dictates that user interface components and navigation must be operable. Users must be able to interact with all controls and interactive elements.

  • Keyboard Accessible: All functionality should be available from a keyboard.
  • Enough Time: Providing users enough time to read and use content.
  • Seizures and Physical Reactions: Avoiding content that is known to cause seizures.
  • Navigable: Helping users navigate, find content, and determine where they are.
  • Input Modalities: Making it easier for users to operate functionality through various inputs beyond a keyboard.

U - Understandable This principle requires that information and the operation of the user interface must be understandable

  • Readable: Making text content readable and understandable.
  • Predictable: Making web pages appear and operate in predictable ways.
  • Input Assistance: Helping users avoid and correct mistakes.

R - Robust This principle states that content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies. This means that as technologies and user agents evolve, the content should remain accessible.

Levels of Conformance​

A – The most basic level, covering the minimum requirements to ensure fundamental accessibility for users with disabilities.

AA – The mid-range level and the most commonly adopted in modern web standards, addressing more significant and frequent barriers to accessibility.

AAA – The highest and most stringent level of conformance, ensuring the best possible accessibility experience. It includes all Level A and AA criteria plus additional enhancements, such as higher color contrast ratios, extended audio descriptions, and simplified language for full inclusivity. Achieving full AAA compliance across an entire site is often considered aspirational.