What is "kerning"

Kern \Kern\, v. t. [imp. & p. p. Kerned; p. pr. & vb. n. Kerning. ] (Type Founding) To form with a kern. See 2d Kern.

n. (cx typography English) The horizontal space between selected pairs of glyphs in a typeface. vb. (present participle of kern English)

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. Kerning adjusts the space between individual letter forms, while tracking (letter-spacing) adjusts spacing uniformly over a range of characters. In a well-kerned font, the two-dimensional blank spaces between each pair of characters all have a visually similar area.

The related term kern denotes a part of a type letter that overhangs the edge of the type block.