The Accessibility Cheatsheet (short version) full → http://bitsofco.de/2015/the-accessibility-cheatsheet/

The-Accessibility-Cheatsheet.md

Principle 1 - Perceivable

1.1 Text alternatives §

For images, use the alt attribute

For audio and video elements, provide text transcripts

For user interface elements, use labels

1.2 Alternatives for time-based media §

provide an alternative time-based media version

1.3 Adaptable Content §

Write your HTML in a meaningful sequence

Meaningful information should not be conveyed solely via sensory characteristics

1.4 Distinguishable §

Contrast ratio of text to background should be at least 4.5:1, preferably 7:1 §

Text should be easily resizable

Use actual text instead of images of text

Control over audio media should be provided

Principle 2 - Operable

2.1 Keyboard accessible §

Ensure all functional elements have a clear focus state

Avoid keyboard traps

2.2 Enough time §

Provide controls for timed content

2.3 Seizures §

Flashing light should not occur more than three times per second

2.4 Navigable §

Provide a link for users to skip to the page’s main content

Titles should be meaningful

Link purpose can be determined from link text

Provide more than one way to locate a web page

Provide information about the current location

Principle 3 - ‘Understandable”

3.1 Readable §

Specify the language(s) of the page

Provide meanings of unusual words and pronunciations of difficult words

Make content available at a lower secondary education reading level

3.2 Predictable §

Consistent navigation

Consistent identification

No unprovoked changes of context

3.3 Input Assistance §

Provide labels and instructions

Error messages in simple language

Error prevention

Principle 4 - Robust

4.1 Compatible §

Write valid code

Specify the purpose of elements