DRONE - A continuous tone or tones of the same pitch. In South Indian music a continuous tone is provided by the tambura, a string instrument that sustains single dominant and tonic tones through the course of a composition or improvisation.

A text summary of the clickable map above, meant for web-crawlers and other automatic tools:
drone is used during composition
drone is used during improvisation
drone has pitch
drone has timbre
drone is continuous tone in South Indian Music
drone is continuous tone in North Indian Music
drone gives no sense of Indian rhythm
drone contains tonic
drone contains dominant
drone is performed by tambura
drone is performed by sruti-peti
drone is performed by Tanpura
drone imbues emotion
drone is category of South Indian instruments
drone is category of North Indian instruments
drone is element of Indian Music