The French horn (since the 1930s known simply as the horn in professional music circles) is a brass instrument made of tubing wrapped into a coil with a flared bell. The double horn in F/B♭ (technically a variety of German horn) is the horn most often used by players in professional orchestras and bands, although the descant and triple horn have become increasingly popular.
As the name indicates, humans originally used to blow on the actual horns of animals before starting to emulate naturally occurring horns with metal ones. The use of animal horns survives with the shofar, a ram's horn, which plays an important role in Jewish religious rituals. Change of pitch was controlled entirely by the lips (the horn not being equipped with valves until the 19th century. Without valves, only the notes within the harmonic series are available. By combining a long length with a narrow bore, the French horn's design allows the player to easily reach the higher overtones which differ by whole tones or less, thus making it capable of playing melodies before valves were invented. In 1818 the German makers Heinrich Stölzel and Friedrich Blümel patented the first valved horn, using rotary valves. François Périnet introduced piston valves in France about 1839. The use of valves, however, opened up a great deal more flexibility for playing in different keys; in effect, the horn became an entirely different instrument, fully chromatic for the first time. Valves were originally used primarily as a means to play in different keys without crooks, not for harmonic playing. That is reflected in compositions for horns, which only began to include chromatic passages in the late-19th century. When valves were invented, generally, the French made smaller horns with piston valves and the Germans made larger horns with rotary valves.
The horn is often used in orchestra, concert band, chamber music, and solo repertoire. Rarely has it been used in jazz. Horn players that play in marching band often play the marching horn or mellophone. A musician who plays a horn is known as a horn player or hornist.