In sailing, the tack is the lower corner of the sail's leading edge. On a sloop rigged sailboat, the mainsail tack is connected to the mast and the boom at the gooseneck. On the same boat, a foresail tack is clipped to the hull and forestay.

Also, a "tack" is the maneuver where a sailboat (yacht) turns its bow through the wind so that the wind changes from one side to the other. Contrast with gybe. In small boats with low booms, the skipper typically announces, "Ready about" to prepare the crew for the tack and the swinging of the boom. Upon the acknowledgement of the crew, the skipper announces, "Coming about" (sometimes alternatively "Helm's a-lee") during the actual tacking. "Coming about" is an alternate term for "tacking".