WCAG 2.0, 2.1, 2.2
Level A
1.1.1 Non-text Content
Images should have descriptive (alt) text.
WCAG 2.0, 2.1, 2.2
Level A
1.2.1 Audio-only and Video-only (Pre-recorded)
Any audio-only content should also be conveyed in text. Any video content with no audio track should also be described in text, but could also be described with audio.
WCAG 2.0, 2.1, 2.2
Level A
1.2.2 Captions (Pre-recorded)
The audio in videos should be captioned.
WCAG 2.0, 2.1, 2.2
Level AA
1.2.4 Captions (Live)
Live videos that include audio should be captioned.
