The top and bottom edges of a square sail are called the HEAD and the FOOT. The outer edge is the LEECH. The main belly or center of the sail is the BUNT. The two top corners are EARINGS and the bottom two corners CLEWS.

Sails are named by their mast and their position on the mast. They are carried on YARDS. A SQUARE YARD is a spar tapered at each end and held at its midpoint at right angles to the mast. The outer end of the yard is the YARDARM. Ropes called BRACES run from each yardarm and allow the yard to be swiveled horizontally to catch the wind. Other ropes called LIFTS from the masthead to the yardarms and SLINGS to the middle of the yard control the vertical movement of the yard by means of HALYARDS. The ropes connected to the clews are known as SHEETS. They are either fastened to the yardarms below or, in the case of the main courses, used to control the sail. CLEWLINES connect the clews to the middle of the sail's spar. BUNTLINES are used in REEFING (making a sail smaller by rolling up part of it ) or FURLING (bundling sails up and securing them to a yard). A FOOT ROPE runs underneath the yards for men to stand on while furling the sails.

All the ropes used to control the sails in working the ship are known as the RUNNING RIGGING as distinct from the STANDING RIGGING which supports the masts. In the latter case SHROUDS go from the masts to the sides of the ship while STAYS (FORE STAYS and BACK STAYS etc.) run fore and aft.

Larger ships than the sloop shown in the illustration carry more sails. Above the Main royal would be the SKYSAIL and the MOONRAKER and there would be STAYSAILS, which are fore and aft sails between the masts. To get the maximum amount of canvas in light winds STUDDING SAILS or STUNSAILS (pronounced stuns`l) were used on either side of the main sails, top sails and top gallants, carried on extensions to the yards. Stunsails are said to be the invention of Sir Walter Raleigh.