What Is Kerning?
Kerning is the adjustment of space between two specific letters to make their spacing look even. Certain pairs — like "AV" or "To" — leave awkward gaps or collisions at default spacing, so kerning tightens or loosens individual pairs. It fine-tunes the rhythm of a word, especially in headlines and logos.
Kerning is pair-specific, which separates it from tracking (overall letter-spacing across a run of text). Well-made fonts ship with hundreds or thousands of built-in kerning pairs.
Designers most often kern by hand in logos and large headings, where uneven gaps are obvious. At body-text sizes the font's automatic kerning is usually enough.