thumb|Sample text in Computer Modern

Computer Modern is the family of typefaces used by default by the typesetting program TeX. It was created by Donald Knuth with his METAFONT program, and was most recently updated in 1992. The Computer Modern typefaces are described in great detail (including full source codes) in the book Computer Modern Typefaces, volume E in the Computers and Typesetting series.

As implied by the name, Computer Modern is a modern font. Modern, or "Didone ," fonts have high contrast between thick and thin elements, and a large x-height relative to the length of ascenders and descenders.

The most unusual characteristic of Computer Modern, however, is the fact that it is a complete type family designed with the METAFONT system. The Computer Modern source files are governed by 62 distinct parameters, controlling the widths and heights of various elements, the presence of serifs or old-style numerals, whether dots such as the dot on the "i" are square or rounded, and the degree of "superness" in the bowls of lowercase letters such as "g" and "o". Computer Modern is by no means the only METAFONT-designed typeface, but it is the most mature and widely used by far.