Saptak (Devanagari: सप्तक) means "gamut" or "the series of seven notes". It denotes the set of swaras, Sa, Re, Ga, Ma, Pa, Dha, Ni which comprise a musical scale in Indian classical music. In Sanskrit, saptak literally means "containing seven" and is derived from the Sanskrit word sapta which means "seven".
The basic saptak is called the Madhya Saptak (Devanagari: मध्य सप्तक). For notes with lower frequencies, the artist may use the Mandra Saptak (Devanagari: मंद्र सप्तक)', which is a lower octave than the Madhya Saptak. For notes with higher frequencies, the upper octave or the Taar Saptak (Devanagari: तार सप्तक) is used.
The usual scale of Indian music spans from Sa in the Madhya Saptak to Sa in the higher, Taar Saptak. This makes eight notes instead of the seven in each Saptak.
Generally, a raga involves notes from three saptaks. The notes in the lower octave are denoted by an apostrophe before the note representation (or a dot below the note representation) and the notes in the upper octave are denoted by an apostrophe after the note representation (or a dot above the note representation).
For example: