The clarinet is a type of woodwind instrument. The name derives from adding the suffix -et (meaning little) to the Italian word clarino (meaning a type of trumpet designed for high-register playing), as the first clarinets had a strident tone similar to that of a trumpet. The instrument has an approximately cylindrical bore, and uses a single reed. A person who plays the clarinet is called a clarinetist or clarinettist.

Clarinets comprise a family of instruments of differing sizes and pitches. The unmodified word clarinet usually refers to the B♭ soprano clarinet, by far the most common clarinet. However, the clarinet family is the largest woodwind family, with more than a dozen types, ranging from the (extremely rare) BBB♭ octo-contrabass to the A♭ soprano (piccolo clarinet). Of these, many are rare or obsolete (there is only one BBB♭ octo-contrabass clarinet in existence, for example), and music written for them is usually played on more common versions of the instrument.