In typography, the x-height or corpus size refers to the distance between the baseline and the mean line in a typeface. Typically, this is the height of the letter x in the font (the source of the term), as well as the u, v, w, and z. (Curved letters such as a, c, e, m, n, o, r and s tend to exceed the x-height slightly, due to overshoot.) However, in modern typography, the x-height is simply a design characteristic of the font, and while an x is usually exactly one x-height in height, in some more decorative or script designs, this may not always be the case.
In typography, kerning (less commonly mortising) is the process of adjusting the spacing between characters in a proportional font, usually to achieve a visually pleasing result. In a well kerned font, the two-dimensional blank spaces between each pair of characters all have similar area. The related term kern denotes a part of a type letter that overhangs the edge of the type block.
In writing and typography, a ligature occurs where two or more graphemes are joined as a single glyph. Ligatures usually replace consecutive characters sharing common components and are part of a more general class of glyphs called “contextual forms”, where the specific shape of a letter depends on context such as surrounding letters or proximity to the end of a line.