Before we can understand the rules laid out in the Web Content Accessibility Guidelines, we must first understand "the 4 W's" of web production.
WWW - The World Wide Web - a world wide computer network. The World Wide Web, which is also known as the Web, is a collection of websites (1.83 billion as of Jan 2021) or web pages stored in web servers and connected to local computers through the internet.
W3C - The World Wide Web Consortium (W3C) is an international community that develops web standards (html, css, etc.) and best practices (web developers and publishers have been following the general guidelines of W3C since 1994.)
WAI – Web Accessibility Initiative (WAI pronounced "why") is an initiative of W3C. The WAI initiative creates standards and guidelines that support and help us understand and implement web accessibility. (this initiative was established in 1997)
WCAG – Web Content Accessibility Guidelines (WCAGpronounced "wkagg") were developed by WAI. This is the document that will list the guidelines that we must follow in order to be compliant. (WCAG 2.1. was released in 2018.)
Web Content Accessibility Guidelines (WCAG) is developed through the World Wide Web Consortium (W3C) in cooperation with individuals and organizations around the world. Their goal is to provide a single shared standard for web content accessibility that meets the needs of individuals, organizations, and governments internationally.
These guidelines are a set of standards meant to help web developers, publishers, content creators, and designers, incorporate criteria that ensures content is accessible and follows best practices.
There are a total of 78 WCAG 2.1 success criteria (includes 2.0 criteria also). See quick reference.
CPABC will need to adhere to 50 success criteria (Level A and AA only)
WCAG 2.0 and WCAG 2.1 are both existing standards. WCAG 2.1 does not deprecate or supersede WCAG 2.0. WCAG 2.1 is backward compatible with WCAG 2.0
Levels A, AA, AAA
Each guideline and criteria requirement is assigned a level or ranking. These levels become progressively harder to achieve.
A (minimal level of requirement—30 criteria items): easiest to do, basic accessibility conformance.
AA (medium difficulty—20 criteria items plus all A criteria items): international best practice requirement.
AAA (most complex—28 criteria items plus all A and AA criteria items): only for specialized sites that have specific features.
To follow WCAG 2.1, CPABC must comply with all AAguidelines. Since, level A is a subset of level AA, we must meet all A and AA criteria items to achieve AA compliance.