On the web, color is a visual design element that is truly without cost. Like images, designers can use colors freely and easily; unlike images, users do not pay the price because color settings do not increase page load or rendering times. Color is a powerful tool for visual design; it can be used to set tone, draw attention, convey information, differentiate elements, and more.
However, color can impair usability. Legibility suffers when the contrast between text and background is insufficient. When text is set with low contrast, character shapes are difficult to distinguish, which makes reading difficult and tiring. For best legibility, complementary elements such as text and background should use complementary colors.