World Wide Web Consortium (W3C) is an international independent group that determines the protocols and standards for the web. A primary initiative of the W3C is to develop accessibility standards, which are known as WCAG (Web Content Accessibility Guidelines).
These guidelines have three levels of success: Level A, Level AA and Level AAA. Level A represents the minimum requirements for accessibility, with Level AAA being the highest level of requirements.
Understanding WCAG 2.0 principles and guidelines
There are 12 guidelines outlined in four main categories:
1. Perceivable - web content is made available to the senses (sight, hearing, and/or touch)
1.1 Text alternatives: provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.
1.2 Time-based media: provide captions and other alternatives for time-based media.
1.3 Adaptable: create content that can be presented in different ways (for example simpler layout) without losing meaning.
1.4 Distinguishable: make it easier for users to see and hear content including separating foreground from background.
2. Operable - interface forms, controls, and navigation are operable
2.1 Keyboard-accessible: make all functionality available from a keyboard.
2.2 Enough time: provide users enough time to read and use content.
2.3 Seizures: do not design content in a way that is known to cause seizures.
2.4 Navigable: provide ways to help users navigate, find content, and determine where they are.
3. Understandable - content and interface are understandable
3.1 Readable: make text content readable and understandable.
3.2 Predictable: make web pages appear and operate in predictable ways.
3.3 Error-recovery: help users avoid and correct mistakes.
4. Robust - content can be used reliably by a wide variety of user agents, including assistive technologies
4.1 Compatible: maximize compatibility with current and future user tools.