On a sailing vessel, a forestay, sometimes called a jibstay, or a headstay, is a piece of standing rigging.^[1] It keeps a mast from falling backwards.^[1] It is usually attached to the very top of the mast.^[1][2] The other end of the forestay is attached to the bow of the boat.^[1]

Often a sail is attached to the forestay.^[1] This sail may be a jib or a genoa.^[1] 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.^[3] A forestay might be made from stainless steel wire or rod.^[4]