The most common example is black characters on a white background. Without anti-aliasing, diagonal edges appear jagged, like staircases, which may be noticeable on a low resolution display. If the display can show intermediate greys then anti-aliasing can be applied. A pixel will be black if it is completely within the black area, or white if it is completely outside the black area, or an intermediate shade of grey according to the proportions of it which overlap the black and white areas. The technique works similarly with other foreground and background colours.