Kerning
In typography, kerning is changing the distance between two letters to make the text easier to read. Usually, this means that letters look equally spaced, and two letters are never too close together or too far apart. If two letters are too close together or too far apart that would make it difficult to read the plain text message.
The purpose of kerning, and most other typography is to make the printed or screen text more legible, that is, easier to read, and also more attractive. A related idea is typographic ligature. This is when two letters are formed so they fit together. In traditional metal type printing, ligatures were formed from lead in certain pairs. It is basically the same idea as kerning, but done automatically.
Kerning Media
The glyph on the right is kerned to overlap the character following it (glyphs are mirrored for printing).
Three versions of "WAR" in the Clarendon typeface: The top version has no kerning, the middle version has some kerning. The bottom version has probably been over-kerned for this character combination: the tightly-spaced "WA" does not balance with the "AR" pair which cannot come closer.
Some words are particularly difficult to space. The name of the Okavango River in southwest Africa is difficult because the letters AVA fit together well, but this makes the spaces on either side seem very large. Either wider or tighter letter spacing may help here.
Kerning contrasted with tracking (letter-spacing): with spacing the "kerning perception" is lost.While tracking adjusts the space between characters evenly, regardless of the characters, kerning adjusts the space based on character pairs. There is strong kerning between the "V" and the "A", and no kerning between the "S" and the "T".
