The tanpura (Sanskrit: तंबूरा, romanized: Taṃbūrā; also referred to as tambura, tanpuri, tamboura, or tanpoura) is a long-necked, plucked, four-stringed instrument originating in the Indian subcontinent, found in various forms in Indian music. Visually, the tanpura resembles a simplified sitar or similar lute-like instrument, and is likewise crafted out of a gourd or pumpkin.

The tanpura is not used to play a melody, but to support and sustain the performance of another musician or vocalist, as well as musicians accompanying a dance performance. The instrument's four strings are tuned to specific notes of a given scale or musical key, normally the fifth (Pa; Solfège, “So”) and the root tonic (Sa; “Do”). The strings are generally tuned 5-8-8-1. One of the three strings tuned to the tonic is thus an octave below the others, adding greater resonance and depth to the ambient drone.

Through continuous, rhythmic plucking of its strings, the tanpura creates a constant harmonic bourdon or drone effect. Uniquely, the tanpura is not played in specific rhythm with the soloist, percussionist, or any other featured musician; the precise timing of plucking a cycle of four strings in a continuous loop is a determinant factor in the resultant sound, and it is played, unchangingly, throughout the whole performance. Tanpurists must keep true to their own rhythm for the duration of the composition, which may be over an hour in some cases, as their drone is critical to the entire musical foundation of the performance. The repeated cycle of plucking the strings in succession creates a sonic canvas on which the melody of the raga (or other composition) is drawn. The sequence of string-plucking is generally (according to pitch) 5-8-8-1, with the fourth and final string plucked being given a slight “rest”, usually two to three seconds, before repeating the cycle. The combined sound of all strings–each string a fundamental tone with its own spectrum of overtones–supports and blends with the external tones sung or played by the soloist.

The Tanpura (or in ancient times called the Tumburu Vina) dates back to approximately 300 B.C. The roots of the instrument are apparent in the Nāṭyaśāstra by Bharata Muni (~200 BCE–200 CE), where drone-based accompaniment is described (though not named Tanpura). References in Sangita Ratnakara (13th century CE) by Sharngadeva also suggest instruments of similar function and structure.

The modern and most current form of the tanpura is depicted from around the 16-17th centuries. While the instrument contains influence from Middle Eastern cultural descent, its closest descendant is the ancient Veena, specifically the Tritantri Veena, also from the Indian subcontinent. Early Mughal paintings during this time illustrated scenes of a tambur player.

Additional evidence of the instrument was seen from the middle of the 17th century. Some portrayals showed a completely wooden, fretless tanpura (Tanjore style), and others shown as a wooden tanpura with a gourd (tumba). These illustrations revealed many different varieties of the instrument.

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.

An electronic tanpura, a small box that imitates the sound of a tanpura, is sometimes used in contemporary Indian classical music performances instead of a tanpura, though this practice is controversial.