European, and especially English, watercraft terminology draws a strong distinction between square-rigged vessels (with square sails hung from yards mounted centrally and horizontally from masts) and fore-and-aft rigged ones (everything else). It is important to note that any other sail (such as a lug or spritsail), "even if it is geometrically square", is not a square sail in the technical sense used in European sail terminology. It is merely a quadrilateral fore-and-aft sail. Vessels are named by the number of square-rigged masts that they have. This is because square-rigged vessels used to be the fastest rig, and more masts were faster.