Heading up is a sailing manoeuvre during which the bow of a boat is turned toward the upwind, or windward, direction without reaching the "irons" point of sail. The boom of the ship never swings from its initial side to the opposite one, showing that tacking has not occurred. Heading up can be accomplished by pushing the tiller towards the sail, so that the rudder moves away from the sail.
Bareing off is the opposite of heading up. In bareing off, the bow of a boat is turned toward the downwind, or leeward direction without reaching the "run" point of sail. The boom does not swing from one side of the boat to the other, which shows that a jibe has not occurred. To bare off, the tiller must be moved away from the sail, so that the rudder moves toward the sail.