This is a woodwind instrument whose sound is produced by blowing against a sharp edge. Flutes may be end-blown, like the recorder, or may have a round shape, like the ocarina; however, the term usually refers to the transverse flute of Western music. The transverse flute, a tubular instrument held sideways to the right, appeared in Greece and Italy by the second century ce. By the 16th century, flutes with finger holes but no keys were in use in Europe. Keys began to be added in the late 17th century. Later 19th-century innovations resulted in the modern flute. The cylindrical tube may be made of wood or, more often, a precious metal or alloy. The flute family also includes the piccolo, the alto flute, and the rare bass flute.