The sitar is said to have been invented in the court of Alaudin Khilzi in Delhi in the 13th Century by the poet Amir Khusro. It evolved from the seh-tar, a Persian instrument with three strings.
The modern instrument has seven plucked strings. Beneath these are eleven to thirteen sympathetic strings which are not plucked but which resonate in harmony with the melody strings. The sitar is a fretted instrument with a gourd base. The frets are movable and the eighth, eleventh, fourteenth and eighteenth are adjusted to the pitch of the scale to be played. A special plectrum called a mizrab is worn on the index finger of the right hand and two fingers of the left hand are used to fret the strings.
In instrumental music the relationship between the sitar and tabla can be thought of as a conversation. Variations of the melody and rhythm of a piece are picked up and passed back and forth between the two instruments during improvisations around the central theme of the music.