The core principles that guide Web Content Accessibility Guidelines (WCAG) include:
Perceivable
You want users to have the ability to perceive all the information that appears on your site, such as text, images, video, and more. Even if a user can’t see your website’s text or listen to your website’s video, you need to provide an alternative.
Operable
You want users to have the capabilities to navigate your site and use all its features. Any user, for example, should have the means to use your main navigation, as well as any site tools, like calculators.
Understandable
You want users to have the means to understand your website content. That means users can understand your site’s text, images, videos, and tools. For example, your site may include instructions for using a feature, like a calculator or a contact form.
Robust
You want users to have the ability to receive the same experience, even if using assistive technologies. People reading your content versus those using a voice reader, for example, should get the same content even if it’s delivered differently.