A musical ensemble is a group of two or more musicians who perform instrumental or vocal music. In each musical style different norms have developed for the sizes and composition of different ensembles, and for the repertoire of songs or musical works that these ensembles perform.

In classical music, trios or quartets either blend the sounds of instrument families (e.g., piano, strings, and winds) or group together instruments from the same instrument family, such as string ensembles or wind ensembles. In jazz ensembles, the instruments typically include wind instruments (one or more saxophones, trumpets, etc.) one or two chordal "comping" instruments (electric guitar, piano, or organ), a bass instrument (electric bass guitar or double bass), and a drummer or percussionist. In rock ensembles, usually called rock bands, there are usually several guitars (one or two electric guitars, a bass guitar, and in some cases, one or more acoustic guitars), a keyboard player (either a Hammond organ, a piano, an electric piano, or an electronic synthesizer), and a drummer.

Classical chamber music

In Western Art music, commonly referred to as classical music, smaller ensembles are called chamber music ensembles. The terms duet, trio, quartet, quintet, sextet, septet, octet, and nonet are used to describe groups of two, three, four, five, six, seven, eight, and nine musicians, respectively.

Five parts

main: quintet The string quintet is a common type of group. It is similar to the string quartet, but with two violas, two violoncellos, or more rarely, the addition of a double bass. Terms such as "piano quintet" or "clarinet quintet" frequently refer to a string quartet plus a fifth instrument. Thus, a piano quintet is usually a string quartet plus a piano. A Mozart's Clarinet Quintet is similarly a piece written for an ensemble consisting of 2 violins, a viola, a cello and a clarinet, the last being the exceptional addition to a "normal" string quartet.

Another common grouping in classical music is the wind quintet, usually consisting of flute, oboe, clarinet, bassoon and horn.

Six or more instruments

A pops orchestra is an orchestra that mainly performs light classical music (often in abbreviated, simplified arrangements) and orchestral arrangements and medleys of popular jazz, music theater, or pop music songs. A string orchestra has only strings, i.e., violins, violas, violoncellos and basses.

A symphony orchestra is an ensemble usually comprising at least thirty musicians; the number of players is typically between seventy and ninety-five and may exceed one hundred. A symphony orchestra is divided into families of instruments. In the string family, there are sections of violins (I and II), violas, violoncellos, and basses. The winds consist of the woodwind family of instruments (flutes and piccolo, oboes and English horn, clarinets up of the Eb Clarinet, Clarinet, and Bass Clarinet, and bassoons including contrabassoon) and the brass family (horns, trumpets, trombones, and tuba). The percussion family includes the timpani, bass drum, snare drum, and any other percussion instruments called for in a score (e.g., triangle, glockenspiel, chimes, cymbals, wood blocks).