Timpani in the context of "Hammer"

An orchestra (/ˈɔːrkɪstrə/ ; OR-ki-strə) is a large instrumental ensemble typical of classical music, which combines instruments from different families. There are typically four main sections of instruments:

• The string section, including the violin, viola, cello, and double bass
• The woodwind section, including the flute, oboe, clarinet, bassoon, and occasionally saxophone
• The brass section, including the French horn (commonly known as the "horn"), trumpet, trombone, cornet, and tuba, and sometimes euphonium
• The percussion section, including the timpani, snare drum, bass drum, cymbals, triangle, tambourine, tam-tam and mallet percussion instruments

Other instruments such as the piano, harpsichord, pipe organ, and celesta may sometimes appear in a fifth keyboard section or may stand alone as soloist instruments, as may the concert harp and, for performances of some modern compositions, electronic instruments, and guitars.

The drum is a member of the percussion group of musical instruments. In the Hornbostel–Sachs classification system, it is a membranophone. Drums consist of at least one membrane, called a drumhead or drum skin, that is stretched over a shell and struck, either directly with the player's hands, or with a percussion mallet, to produce sound. There is usually a resonant head on the underside of the drum. Other techniques have been used to cause drums to make sound, such as the thumb roll. Drums are the world's oldest and most ubiquitous musical instruments, and the basic design has remained virtually unchanged for thousands of years.

Drums may be played individually, with the player using a single drum, and some drums such as the djembe are almost always played in this way. Others are normally played in a set of two or more, all played by one player, such as bongo drums and timpani. A number of different drums together with cymbals form the basic modern drum kit. Many drums are played together with other instruments.

Program music or programmatic music is a type of instrumental music that attempts to musically render an extramusical narrative or description of some aspect of world. The term was invented in the 19th century by Franz Liszt, who himself composed a great deal of program music. However, as Liszt himself noted, program music had been written for centuries before his time.

To give an example, Ludwig van Beethoven's Sixth Symphony narrates a visit to the countryside, portraying in succession a happy arrival, a quiet moment by a brook, an encounter with dancing peasants, a thunderstorm, and the peasants' song of thankgiving when the storm is over. Program music is often written so that the notes themselves convey, at least to some degree, the meaning of what is portrayed; thus the thunderstorm in Beethoven's symphony includes loud timpani strokes to convey the thunder and shrill piccolo music to depict the shrieking winds.

A percussion instrument is a musical instrument that is sounded by being struck or scraped by a beater including attached or enclosed beaters or rattles struck, scraped or rubbed by hand or struck against another similar instrument. Excluding zoomusicological instruments and the human voice, the percussion family is believed to include the oldest musical instruments. In spite of being a very common term to designate instruments, and to relate them to their players, the percussionists, percussion is not a systematic classificatory category of instruments, as described by the scientific field of organology. It is shown below that percussion instruments may belong to the organological classes of idiophone, membranophone, aerophone and chordophone.

The percussion section of an orchestra most commonly contains instruments such as the timpani, snare drum, bass drum, tambourine, belonging to the membranophones, and cymbals and triangle, which are idiophones. However, the section can also contain aerophones, such as whistles and sirens, or a blown conch shell. Percussive techniques can even be applied to the human body itself, as in body percussion. On the other hand, keyboard instruments, such as the celesta, are not normally part of the percussion section, but keyboard percussion instruments such as the glockenspiel and xylophone (which do not have piano keyboards) are included.

The percussion section is one of the main divisions of the orchestra and the concert band. It includes most percussion instruments and all unpitched instruments.

The percussion section is itself divided into three subsections: