, the bottom corner of a sail opposite the end touching the mast
Most sails have a grommet at their clew so they can be tied down to the boom. Usually a rope called an Outhaul is used to provide tension, stretching the sail. The tighter the sail, and less baggy, the more wind can skim off of it, giving more control for less power. This outhaul can be placed in a block or a cleat so it can be adjusted constantly during a race.