This is probably an really easy one so I figured I'd ask it while I'm still a newbie and get it out of the way. Is it common for a chord progression (written by your guitar player) to contain notes from the key of the song? For instance, if a song is in Amaj, will the chord progression be likely to contain the notes from the Amaj scale? Is it just as likely to contain notes from outside of that scale? It's amazing how long I've gotten by without knowing the answer to this. I guess the real question I'm asking is... Does the key of a song have an impact on the chords that can be chosen to create that song? My gut instinct is telling me no, because I'm sure if I sat down and played some bass lines to some songs I know, I would find a song in the key of Amaj that contained some chords outside of the Amaj scale. But then I thought perhaps I would come to find that the song was not in fact in the key a Amaj at all... I hope this isn't all nonsense. I just need a push in the right direction with this. Thanks again!