On a sailing vessel, a forestay, sometimes called a jibstay, or a headstay, is a piece of standing rigging. It keeps a mast from falling backwards. It is usually attached to the very top of the mast. The other end of the forestay is attached to the bow of the boat.
Often a sail is attached to the forestay. This sail may be a jib or a genoa. In a cutter rig, the jib or jibs are flown from stays in front of the forestay, perhaps going from the masthead to a bowsprit. The sail on the forestay is then referred to as the staysail. A forestay might be made from stainless steel wire or rod.