Contrast
Contrast is the core factor in whether or not text is easy to read. Good
contrasts will make text easy on the eyes, easy to scan quickly, and overall
more readable. On the other hand, poor contrast will force the user to
squint and make reading the body text almost painful, not to mention a lot
slower.
As shown in the following illustration, black on white is very readable.
Black on white is obviously the standard contrast colors, and to achieve
readable content it is good to stay in the range of black-on-white contrast.
This one, however, pink on blue, is nearly impossible to read. This example
my be a little extreme, but it shows how such an awful contrast can have a
major impact on the text. You probably won՚t see Web sites using such
poor contrast, but it still shows why you need to be very smart about it.