Chamber music is a form of classical music, written for a small group of instruments which traditionally could be accommodated in a palace chamber. Most broadly, it includes any art music that is performed by a small number of performers with one performer to a part. The word "chamber" signifies that the music can be performed in a small room, often in a private salon with an intimate atmosphere. However, it usually does not include, by definition, solo instrument performances.

Because of its intimate nature, chamber music has been described as "the music of friends." For more than 200 years, chamber music was played primarily by amateur musicians in their homes, and even today, when most chamber music performance has migrated from the home to the concert hall, there are still many musicians, amateur and professional, who continue to play chamber music for their own pleasure. Playing chamber music requires special skills, both musical and social, which are different from the skills required for playing solo or symphonic works.

Johann Wolfgang von Goethe described chamber music (specifically, string quartet music) as "four rational people conversing." This conversational paradigm has been a thread woven through the history of chamber music composition from the end of the 18th century to the present. The analogy to conversation recurs in descriptions and analyses of chamber music compositions.