X-height

In typography, the x-height or corpus size refers to the height of the letter 'x' in any font, which is usually the same for a, c, e, m, n, o, r, s, u, v, w, and z. Letters whose height is greater than the x-height, either have descenders which extend below the baseline, such as y, g, q, and p, or have ascenders, which extend above the x-height, such as l, k, b, and d. The ratio of the x-height to the body height is one of the major characteristics that defines the appearance of a font.

See also