The adjustment of space between a specific pair of letters to correct optical unevenness. Distinct from tracking, which spaces all letters uniformly.
Kern the ‘AV’ in the logotype. At display size the default gap reads as a hole.
Kerning is a per-pair correction; tracking is a global setting.
Confusing the two is the most common typographic vocabulary mistake. In
practice you only hand-kern at display sizes: body text relies on the font’s
built-in kern tables, and font-kerning is on by default in every browser.