PERCEIVABLE

Information and user interface components must be presentable to users in ways they can perceive.

• Use ALT tags for images and text descriptions for animations, 3D models and other media.
• Provide captions for video and audio transcriptions for audio.
• Use appropriate semantic markup for table headers and forms.
• Ensure appropriate contrast between text and background.
• Use CSS formatting instead of graphics to format text whenever possible.

UNDERSTANDABLE

Information and the operation of user interface must be understandable.

Identify language of text or subsection of text with a language code.
Avoid unannounced pop up windows.
Provide a separate Submit or Go button/link to initiate page changes (versus autosubmit upon selection).
Provide usable instructions for entering information into forms and applications (preferably before the form field).

OPERABLE

User interface components and navigation must be operable. 

• All form and application controls can be operated from a keyboard.
• Users are given mechanisms to skip repetitive content.
• Scrolling or blinking text can be paused.
• Landmarks are provided to assist in screen reader navigation, e.g. meaningful page title, meaningful headers and meaningful and unique hyperlink text.

ROBUST

Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.

Use validated markup.
Label the name and role of all user interface components.
Identify the value for all data fields, including parameters for interface controls.