The tanpura (or tambura, tanpuri) is a long-necked plucked string instrument found in various forms in Indian music; it does not play melody but rather supports and sustains the melody of another instrument or singer by providing a continuous harmonic bourdon or drone. A tanpura is not played in rhythm with the soloist or percussionist: as the precise timing of plucking a cycle of four strings in a continuous loop is a determinant factor in the resultant sound, it is played unchangingly during the complete performance. The repeated cycle of plucking all strings creates the sonic canvas on which the melody of the raga is drawn. The combined sound of all strings, each string a fundamental tone with its own spectrum of overtones, is a rich and vibrant, dynamic-yet-static tone-conglomerate, due to interactive harmonic resonances that will support and blend with the external tones sung or played by the soloist.
The name tanapura is derived from tana, referring to a musical phrase, and pura, which means "full" or "complete".Hindustani musicians favour the term 'tanpura' whereas Carnatic musicians say 'tambura'; 'tanpuri' is a smaller variant used for accompanying instrumental soloists.
Tanpuras form the root of the ensemble and indeed of the music itself, as the tanpura creates an acoustic dynamic reference chord from which the ragas (melodic modes) derive their distinctive character, color and flavor. Concerning its history, A. D. Ranade states: "The first unambiguous reference to the tanpura is in Sangeet Parijat (1620). It is neither mentioned by the earlier texts nor does it find a place in sculptures". Stephen Slawek notes that by the end of the 16th century, the tanpura had "fully developed in its modern form", and was seen in the miniature paintings of the Mughals. Slawek further suggests that due to structural similarity the sitar and tanpura share a related history.
An electronic tanpura, a small box that imitates the sound of a tanpura, is often used in contemporary Indian classical music performances instead of, or in addition to a tanpura, primarily in Carnatic music, though this practice is controversial amongst aficionados of high level Classical music. A 2006 article in the performing arts magazine Sruti notes: "Any model electronic tanpura produces a sound that is necessarily artificial, which is the opposite of artistic. The electronic substitute has no artistic value and has nothing to teach us but repetitive unnatural boredom."