Fascia
Fascia is the board that runs along the edge of the roof, right behind the gutter. Because the gutter hangs on it, fascia is usually the first place damage shows up when a gutter overflows, leaks at a seam, or holds standing water against the wood. Replacing a rotted fascia board without fixing whatever soaked it just means the new board fails on the same timeline the old one did, so we look at the cause, not only the board.