what do the numbers behind a chord (guitar) represent?

Question

for example...A7, G7, etc...
what do they mean?

Answer 1

It's theory notation - that also tells the guitair player which notes to play in the chord.

A normal 'A' chord is A C# E A
an A7 is A C# E G and usually leads to a D chord D F# A

good question

Answer 2

7th is the type of chord. seventh is the most popular but there is also 5ths and 9ths and more. What it means is to remove the seventh note in the chord. It may not mean much but for example....an A CHORD is usually 0 0 2 2 2 0 tabed and an A7 CHORD is 0 0 2 0 2 0 see i removed the A in it.

Answer 3

They represent the dominant interval in the chord. For instance, in the key of A, from A to B is a 2nd, A to C is a minor 3rd interval, A to C# is a major 3rd, D is a 4th, E - 5th, F# - 6th, G - 7th/m7, G#(Ab) - maj7th interval.

These notes, minus the minor notes are all the notes that make up the major scale.

Play an A7 or and Am7 and see if there is a G# note in there. I bet there is.