Woodwind instruments are a family of musical instruments within the greater category of wind instruments. Common examples include flute, clarinet, oboe, bassoon, and saxophone. There are two main types of woodwind instruments: flutes and reed instruments (otherwise called reed pipes). The main distinction between these instruments and other wind instruments is the way in which they produce sound. All woodwinds produce sound by splitting the air blown into them on a sharp edge, such as a reed or a fipple. Despite the name, a woodwind may be made of any material, not just wood. Common examples include brass, silver, cane, as well as other metals such as gold and platinum. The saxophone, for example, though made of brass, is considered a woodwind because it requires a reed to produce sound. Occasionally, woodwinds are made of earthen materials, especially ocarinas. Flutes Flutes produce sound by directing a focused stream of air below the edge of a hole in a cylindrical tube. The flute family can be divided into two sub-families: open flutes and closed flutes. To produce a sound with an open flute, the player is required to blow a stream of air across a sharp edge that then splits the airstream. This split air stream then acts upon the air column contained within the flute's hollow causing it to vibrate and produce sound. Examples of open flutes are the transverse flute, panpipes, and shakuhachi. Ancient flutes of this variety, including bamboo flutes, were often made from tubular sections of plants such as grasses, reeds, bamboo and hollowed-out tree branches. Later, flutes were made of metals such as tin, copper, or bronze. Modern concert flutes are usually made of high-grade metal alloys, usually containing nickel, silver, copper, or gold. To produce a sound with a closed flute, the player is required to blow air into a duct. This duct acts as a channel bringing the air to a sharp edge. As with the open flutes, the air is then split; this causes the column of air within the closed flute to vibrate and produce sound. Examples of this type of flute include the recorder, ocarina, and organ pipes. Reed instruments Reed instruments produce sound by focusing air into a mouthpiece which then causes a reed, or reeds, to vibrate. Similarly to flutes, reed pipes are also further divided into two types: single reed and double reed. Single-reed woodwinds produce sound by