The galeas Albanus
with four staysails as headsails, or jibs: (left to right) flying jib, outer and inner jib and "the" staysail
A headsail of a sailing vessel is any sail set forward of the foremost mast. The most common headsails are staysails, a term that includes jibs and the larger genoa. Other headsails are set independently of any forestays, such as the spinnaker.
Some headsails can only be flown on specific points of sail, such as the spinnaker, which is only flown when sailing downwind, the Asymmetrical spinnaker and the gennaker, used when sailing a course between downwind and close hauled.