principle: Understandable
Make sure that everyone can understand or comprehend the same content and components. Can people understand this content with whatever capacity they have?
3.1.1 Language of Page
There’s a lang attribute on the <html> element that matches the language of the page.
3.1.2 Language of Parts
Any parts of the page that are in a different language to the page itself are marked up with the appropriate lang value. Names and phrases derived from other languages, like “Déjà vu” in English, don’t need this.
3.1.3 Unusual Words
Jargon and figurative language is avoided, or, where not it’s possible, the words are defined or clarified the first time they’re used on a page.
3.1.4 Abbreviations
Acronyms and shortened words should be avoided when possible. When they are used, they must be defined the first time they appear on a page.
3.1.5 Reading Level
Content is written in a way that most people with a lower secondary education (around 8th or 9th grade) can understand, or a simpler version is provided.
3.1.6 Pronunciation
If a word can be pronounced more than one way, and each way has a different meaning, the meaning is clarified to avoid ambiguity.
3.2.1 On Focus
Nothing unexpected changes when something on the page receives keyboard focus, like a <button>
3.2.2 On Input
Nothing unexpected happens when a form field value is selected, like picking an option from a dropdown menu.
3.2.3 Consistent Navigation
Navigation is consistent from page to page.
3.2.4 Consistent Identification
Things that carry out a particular function must always look and work the same.
