Why equal spacing can look unequal
Letters are not neat boxes of the same width. Their outlines leave different amounts of open space: the diagonal strokes of A and V, for instance, form a wedge that can look larger than the gap between two straight-sided letters. If every character is placed at the same measured distance from the next, the line may therefore feel lopsided.
Kerning corrects the pair, not the whole line
A typeface sets a default amount of space around each letter. Kerning is an additional adjustment to the gap between a particular pair. A designer can move A and V closer together so their shapes appear more evenly separated, without changing the spacing of every other pair. Other combinations may need the opposite treatment if their forms crowd one another.
The adjustment is visual rather than geometric: the goal is not to make the empty regions mathematically identical, but to make the letters seem balanced when read. That judgment depends on the letter shapes, the typeface, and the size at which the text appears.
Why the small correction matters
A poorly spaced pair can interrupt the rhythm of a word, especially in a large headline or a short label where the letters are easy to inspect. Well-kerned type lets the eye move across the word without being snagged by an accidental-looking gap. The wedge between A and V may still be physically wider than another space; it simply no longer looks like the letters have drifted apart.
