Sail

From Conservapedia

A Sail is any surface used to harness wind power in order to provide propulsion. The most common sails are made of cloth, though modern sails are made of various man-made materials. The most basic arrangement on a sailing vessel is a single sail called a mainsail, though this arrangement does not allow a ship to sail against the wind. The addition of a second sail on the forward part of a ship, called a jib, allows the ship to tack against the wind (moving in a zig-zag pattern along a central axis with the ultimate result being forward movement against the wind). During the Age of Sail, ships would use dozens of sails to most effectively harness the wind and thus achieve superior speeds.