Percussion mallet in the context of "Triangle (musical instrument)"

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.

A keyboard percussion instrument, also known as a bar or mallet percussion instrument, is a pitched percussion instrument arranged in the same pattern as a piano keyboard and most often played using mallets. While most keyboard percussion instruments are fully chromatic, keyboard instruments for children, such as ones used in the Orff Schulwerk, may be diatonic or pentatonic.

Despite the name, keyboard instruments such as the celesta and keyboard glockenspiel are not considered keyboard percussion instruments, despite being idiophones, due to the different skillsets required to play them. This is because keyboard percussion instruments do not possess actual keyboards, but simply follow the arrangement of the keyboard.

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 glockenspiel (/ˈɡlɒkənʃpiːl/ GLO-kən-shpeel; German pronunciation: [ˈɡlɔkənˌʃpiːl] or [ˈɡlɔkn̩ˌʃpiːl], Glocken: bells and Spiel: play) or bells is a percussion instrument consisting of pitched aluminum or steel bars arranged in a keyboard layout. This makes the glockenspiel a type of metallophone, similar to the vibraphone.

The glockenspiel is played by striking the bars with mallets, often made of a hard material such as metal or plastic. Its clear, high-pitched tone is often heard in orchestras, wind ensembles, marching bands, and in popular music.

Crotales (/ˈkroʊtɑːlz/, /ˈkroʊtəlz/), sometimes called antique cymbals, are percussion instruments consisting of small, tuned bronze or brass disks. Each is about 10 cm (4 in) in diameter with a flat top surface and a nipple on the base. They are commonly played by being struck with hard mallets. However, they may also be played by striking two disks together in the same manner as finger cymbals, or by bowing. Their sound is rather like a small tuned bell, only with a much brighter sound and a much longer resonance. Similar to tuned finger cymbals, crotales are thicker and larger; they also have slight grooves in them. The name comes from the Greek crotalon, for a castanet or rattle.

Modern crotales are arranged chromatically and have a range of up to two octaves. They are typically available in sets (commonly one octave) but may also be purchased individually. Crotales are treated as transposing instruments; music for crotales is written two octaves lower than the sounding pitch to minimize ledger lines.