The summary.
IT BENEFITS FAR MORE PEOPLE THAN USUALLY CREDITED
Permanent impairments, temporary ones, and everyone in bright sunlight, on a poor connection, or with one hand occupied.
THE FOUR THINGS THAT ADDRESS MOST PROBLEMS
Sufficient contrast, keyboard access, labels on every control, and real headings in order.
TEST WITH THE KEYBOARD ALONE
Every action must be reachable, focus must always be visible, and nothing may trap it.
Never remove the focus indicator. Replace it with something better, never nothing.
NEVER LET COLOUR CARRY MEANING ALONE
View the interface in greyscale — that reveals everything depending on hue.
Underline links within body text.
WRITE ALTERNATIVE TEXT FOR WHAT THE IMAGE CONVEYS IN CONTEXT
The same photograph needs different text depending on why it is there. Mark decorative images so they are skipped.
Better still, never put text in images.
ALLOW TEXT TO BE ENLARGED
Many people do so by default, and a layout that breaks when text grows fails them. Test at double size.
MAKE TARGETS LARGE AND WELL SPACED
Particularly where one action is destructive. Prefer undo over confirming everything.
AUTOMATED TOOLS ARE NECESSARY AND INSUFFICIENT
They cannot tell whether alternative text is meaningful or whether the interface is usable.
