The tambura, also known as tanpura or tanpuri (for smaller variants),  is a standard addition to classical Indian music ensembles dating back to the 16th century. It provides a harmonic drone, or base note (adharaswara) which acts as a backdrop to rhythm (talas) and melodies (ragas). It has a resonator, strings, and no frets because it is always played whole. Its name derives from the phrases tana (musical phrase) and pura (whole).

Harmonic drones in Indian classical music have existed in other instrumental forms since ancient times, in other stringed instruments as well as the wind instrument ottu. The tambura is believed to be derived from the sitar, another stringed instrument with drone strings. 

Below are instructions on playing technique:

“A Tanpura can be held and played upright resting either on the lap or on the floor, or it is placed horizontally on the lap or on the floor in front of the player. The classical playing technique requires putting the thumb of the playing hand to the neck of the Tanpura so that it serves as a support. The strings are plucked in a way which allows the fourth string to echo a little longer, and also should not be uniform so that it may “convey the impression of a freely floating, lively vibration.“