Accessible sites have enough contrast, real headings, labeled forms and work without a mouse.

Screen readers read the alt text instead of the picture. Search engines use it to understand what an image shows.

Example. A café writes “Two flat whites on a marble table by the window” instead of “image1.jpg”.

Body text needs a contrast ratio of at least 4.5 to 1 to be readable for most people, large text at least 3 to 1.