A short, decorative stroke used to finish off the stroke of a letter.
output: The little ledges or other embellishments on the ends of letters which make them easier to read.
Fonts with little hooks (called serifs) on the ends of the font. The serifs usually help make the font more readable. However, serifs are quite difficult to render on low resolution devices, especially at small font sizes (because they are a fine detail), so it is often true that at small sizes on low resolution devices, sans serif fonts (such as Microsoft's Verdana) prove more readable. Another issue is that there are sans serif fonts (like the moderns) that are not designed for writing long documents.
The short crossline or curl like terminals at the extemes of the strokes of Roman lettering.