Ok, Im learning music theory at the minute and doing pretty well with it. Something Confuses me though. When Playing a chord, do all the notes played in it have to be in that key? (obviously excluding the root note) Sorry If its a vague explaination.
They don't have to be anything; there aren't any rules to follow in music theory, just descriptions of relationships. If it sounds good, it is good.
in basic theory, when you get more advanced you'll basically just break all the rules as long as it sounds good.
Quote by Liam616
ok thanks guys. That just had me confused for a while

Yeah take a basic twelve bar blues rhythm for example, each chord is traditionally a 7 chord, so I7 IV7 and V7, which does not exist in the common major scale. Don't take this example to heart, there are so many other possibilities, just use what sounds good to you and that's it, nothing else matters.