Originally Posted by: Swe_ShredderIve learnt those 7 scales that you provided there, those are just to play over a Gmaj chord right? Or can I solo on all 7 scales if the chord structure is like G, C, D, G ? Or G,D,Am,Em?

This is where modes come into play, actually. Look at all the notes in the Gmaj (Ionian) scale: G, A, B, C, D, E, F#, G. Now, the Ionian scale starts AND ends on G. The Dorian is the second mode which starts and ends on A: A, B, C, D, E, F#, G, A. Phrygian is the third and begins and ends on the third note, etc. So if you are playing a solo over, say, G, C, D, G... when the G chord is being played, play a lick in G Ionian, When the C is played use C phrygian, etc... It's very helpful if the chords in the progression can be found in the key tone scale. i.e. all the chords you gave above are in the Gmaj scale, which makes it whole lot easier. So as long you know the modes, and play a scale that relates to the chord(s), you'll be alright.