Between the seven swaras lie finer gradations of pitch called shrutis — microtones smaller than a Western semitone. The classical texts count twenty-two shrutis in an octave, and the precise tuning of a swara within its shruti-band is part of what gives a raag its exact flavour.
This is why two raags can use "the same" komal Ga yet sound subtly different: each places the note on a slightly different shruti. The expressive slides (meend) and oscillations (andolan) of Hindustani music move through these microtonal spaces.
The word shruti also names the drone — the tanpura sounds the Sa and Pa against which every other pitch is heard.