Cover of George Harrison
Check out this video from YouTube of George Harrison and some of his musician buddies doing his song, "I Saw Her Standing There". That song of course is just one of the many many great songs from the Beatles early years.
What I noticed that I thought was cool about this video is...check out the guy singing and playing keyboard (which you can't see but it obvious that's what he's playing). At the .52 mark on the video he holds his left hand up.
You know what he's doing?
He's giving chord signals!
There's only 3 chords that make up traditional rock 'n roll.... the I, the IV and the V (or V7).
The chords are often referred to by their numbered order in the scale. Thus the I Chord in the Key of C major would be C-E-G, Ok? The IV chord would be F-A-C.....and so on. Sometimes they'll add an extra note there called the 'seventh'. ...especially on the IV and V chords.
But anyway....that's what this guy is doing. Cool isn't it? He's like a 'drum major' leading his group.
I think the guy in the video also slips a vi (which would be A....it could be A maj or A minor).
This is all assuming the song is in the key of C of course. Which it usually isn't. The reason for that is because most rock 'n roll is based on what's easiest for guitar players. And the key of A or E is easiest for most guitar players.
I LOVE THE BEATLES!