Marimbas are wooden keyboard instruments. They are normally struck with two, three or four mallets and played by one or two players¹. The keyboard layout the marimba uses is similar to that of a piano, with the accidentals (known as black notes on a piano) set behind and slightly above the natural notes (known as white notes on a piano). Long resonating tubes (usually made of aluminium or brass) hang below each note. Each one is tuned to the pitch of the bar above it. The sound produced by a marimba is referred to as being 'mellow' and similar to an organ.

A typical marimba will include around five octaves (65 notes) of rosewood² bars of different lengths in keyboard format. The bars are usually mounted on a frame, and the instrument is around 2 metres long. Western models have rigid frames with adjustable heights and are played standing. However, similar instruments from Africa and Asia are floor-mounted and played seated.

The marimba is played with mallets usually wound at one end with wool or coloured nylon. Mallets range from very soft, fluffy mallets to hard rubber mallets with no wool padding. The wool is usually dyed in a colour to indicate the hardness of the mallet. Softer mallets make a quiet sound and harder mallets make a harsher, louder sound. Percussion mallets are different from sticks; sticks are not used to play a marimba.

The art of playing the marimba is considered one of the hardest of to master out of all percussion instruments. The keys are either struck in sequence, played as single chords or 'rolled'. The player usually holds one mallet in each hand, although trickier pieces may call for three or four mallets, in which case two are held in each hand. Being able to co-ordinate four different mallets with only two hands is considered one of the greatest skills marimbists have. Obviously being able to hit four notes at a time can make better sounding chords than only two, and brings marimbists one step closer to pianists, who can use eight fingers and two thumbs.

Each wooden bar of a marimba makes the sound of one note. The best tone quality is obtained by striking the bar somewhere between the middle and each end. Hitting the bar in the middle will result in a 'dead' sound.

Most marimbists are percussionists and have managed to master many other percussion instruments as well, including the xylophone, vibraphone and glockenspiel. Those three instruments are very closely related to the marimba³.

Music for the marimba is written as traditional Western manuscript. The marimba player should be familiar with bass clef as well as treble clef, as they will often be required to play in both. In some countries marimba music is rarely written down.

Marimbas can be played solo as part of a percussion recital, but are usually part of a percussion ensemble. In percussion ensembles marimbas will either provide the melody or a bass line to the piece of music. Marimbas are occasionally used in orchestras, usually for 20th Century music, as a sound effect or as a solo instrument. The marimba had long solos in the soundtrack to the film American Beauty.

The word marimba is thought to come from an African Bantu word rimba (probably meaning 'keys' or 'notes') with the prefix ma (meaning 'many'). The instrument itself seems to come from South or Middle America (specifically Guatemala), thought to have been introduced by either African slaves or pre-Columbian African contact. Similar instruments have evolved in Asia. As what appears to be a stone version of the marimba dating back to 3000 BC has been found, the marimba is considered the oldest instrument in the world.

The marimba is the national instrument in Guatemala, where it is often used for ceremonies. It is used in a similar way in other nearby countries.

Some notable marimbists are Evelyn Glennie, Nebojsa Zivkovik and Leigh Stevens - who founded an annual Marimba Seminar. These people are amongst the best at what they do in the world although there are many other excellent players, with more appearing as the instrument becomes increasingly popular.