There are seven modes. Each mode identifies which note of a scale you should start with. Let’s say you are playing in the 2nd mode (Dorian mode) of a C major scale. That means you will start and end on the 2nd note of the C major scale. The notes in C major are C, D, E, F, G, A, and B. So in the second mode you are starting and ending with the second note D – while playing the other notes in the C major. If playing the third mode (phrygian) of scale, you start and end on the third note – E, fourth mode (lydian) starts on fourth note – F, etc…
Bass Player Center – Home Page
There are seven modes