The clarinet is a wind instrument consisting of cylindrical wood (or occasionally metal) pipe with a bell-shaped opening at one end and a mouthpiece at the other end, to which a reed is attached. Generically, the clarinet is any member of the woodwind family, whose enclosed air column is achieved by a single reed, as opposed to the double-reed instruments of the principal treble woodwind of the concert band and is used extensively in solo, chamber, and popular music.
The clarinet is a transposing instrument. Its part in the score is written at a pitch different from the one actually sounded. The immediate ancestor of the clarinet was the chalumeau, a short, cylindrical pipe with seven finger holes and a reed cut in its upper side, but without a bell-shaped opening. The clarinet was invented when Johann C. Denner doubled the length of the chalumeau and added two keys, making possible the clarino, the upper of trumpetlike, register. Early clarinets was made in many more size than are produced today. The number of different sizes needed was reduced in the early 19th century by adding more keys to the instrument. The B-flat clarinet is most common today; next is the clarinet is A. The B-flat clarinet is about 60 cm (23.6 in) long and has a range of more than three octaves.
Since the end of the 19th century, a D clarinet and a bass clarinet in B-flat have been used in large orchestras. Concert bands commonly use a small E-flat clarinet, pitched a fourth above the B-flat clarinet; an alto clarinet in E-flat, pitched a fifth lower than the B-flat clarinet; and a bass clarinet, pitched an octave lower than the standard instrument, these constitute the clarinet choir, A double-bass, or contrabass, clarinet is pitched two octaves lower than the standard B-flat clarinet.