The clarinet is a musical instrument of woodwind type. The name derives from adding the suffix -et (meaning little) to the Italian word clarino (meaning a type of trumpet), 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. In jazz contexts, it has sometimes been informally referred to as the "licorice stick.

Clarinets comprise a family of instruments of differing sizes and pitches. The clarinet family is the largest such woodwind family, with more than a dozen types, ranging from the BB♭ contrabass to the A♭ soprano. Of these, many are rare or obsolete, and music written for them is usually played on the common types. The unmodified word clarinet usually refers to the B♭ soprano clarinet, by far the most commonly played clarinet.

A person who plays the clarinet is called a clarinetist or clarinettist. Johann Christoph Denner invented the clarinet in Germany around the turn of the 18th century by adding a register key to the earlier chalumeau. Over time, additional keywork and airtight pads were added to improve tone and playability. Today, the clarinet is used in jazz and classical ensembles, in chamber groups, and as a solo instrument.