WCAG stands for Web Content Accessibility Guidelines. They are the most important guidelines for web accessibility policy and set the standard for the web accessibility legislation in most countries across the world.
In order to properly understand why WCAG 2.1 is so important, you need to know the Institution that conceived it. The WCAG was created by the World Wide Web Consortium, known as the W3C. This was founded in the halls of the MIT Computer science Laboratory (MIT/LCS) in October 1994, when global web activity was beginning to increase exponentially. The organization is comprised of over 440 members including business leaders, non-profit organizations, universities, government agencies and relevant industries, as well as top scientists in the field.
Originally, the W3C focused on standardizing web protocols so that websites and web tools would be compatible with each other. Every W3C standard is reviewed several times, tested and analysed before being approved by members. Typically, W3C standards have 3 levels of compliance, from A to AAA.
Web accessibility was one of the first issues addressed by W3C. The first WCAGs were published in 1999, revised in 2008 as WCAG 2.0 and updated again in the form that we use today, 2.1 in 2018.
All website content must be able to be read accurately and clearly by screen-readers and assistive software installed on the operating system and used by people with visual impairments to access digital navigation content.
User interface and design compatible
You must implement a sufficient colour contrast ratio between foreground and background elements, set correct and readable font sizes, have a sufficient text spacing, text emphasis and other design and user interface adjustments.
Can be understood by people with cognitive impairments
Content must be written in very simple, comprehensible words or alternatively it must include a glossary or dictionary to help readers with cognitive impairments properly understand it.
Keyboard navigation compatible
Website must be completely navigable and operable using only the keyboard, without the need for a mouse. This feature is used by people with mobility impairments.
Safe from epilepsy episodes
Animations must be able to be stopped so that people with epilepsy can safely navigate without risking a seizure
WCAGs are not a set of laws that must be enforced, but many governments have adopted them as standards for their accessibility legislation.
Complying with WCAG is the best mean of achieving compliance with most global legislation.