Why “AV” often needs less space
Letters occupy invisible rectangular areas called glyphs. A font assigns each glyph a width and a default gap before the next one. That system works well for many pairs, but it can leave an obvious hole between letters whose shapes angle away from each other.
An uppercase A has sloping sides, while a V opens toward the top. Put them side by side and their outlines leave more empty space than a reader’s eye expects. The letters may be technically separated by the usual spacing rules, yet the word can look as if it has a break in it.
Kerning corrects a particular pair
Kerning changes the spacing between specific neighboring letters. For A and V, a designer or font file can shift the V closer to the A, reducing the visible gap without changing either letter’s shape. The goal is not to make the outlines touch; it is to make the space between them look consistent with the spaces elsewhere in the word.
That judgment is visual rather than purely mathematical. Two pairs can have the same measured gap but appear different because the surrounding shapes frame empty space differently. Kerning lets typography account for that optical effect.
Kerning is also distinct from tracking, which increases or decreases spacing across a whole stretch of text. A word might receive tighter tracking overall and still need an individual pair adjustment. When kerning works, it is hard to notice: the letters simply read as a connected word rather than as separate shapes.
