Sonata (/səˈnɑːtə/; Italian: [soˈnaːta], pl. sonate; from Latin and Italian: sonare [archaic Italian; replaced in the modern language by suonare], "to sound"), in music, literally means a piece played as opposed to a cantata (Latin and Italian cantare, "to sing"), a piece sung. The term evolved through the history of music, designating a variety of forms until the Classical era, when it took on increasing importance. Sonata is a vague term, with varying meanings depending on the context and time period. By the early 19th century, it came to represent a principle of composing large-scale works. It was applied to most instrumental genres and regarded—alongside the fugue—as one of two fundamental methods of organizing, interpreting and analyzing concert music. Though the musical style of sonatas has changed since the Classical era, most 20th- and 21st-century sonatas still maintain the same structure.

The term sonatina, pl. sonatine, the diminutive form of sonata, is often used for a short or technically easy sonata.

In the Baroque period, a sonata was for one or more instruments almost always with continuo. After the Baroque period most works designated as sonatas specifically are performed by a solo instrument, most often a keyboard instrument, or by a solo instrument accompanied by a keyboard instrument.

Sonatas for a solo instrument other than keyboard have been composed, as have sonatas for other combinations of instruments.