C7/G
C Dominant 7th over G · 3 fingerings
A slash chord: a C dominant seventh with G in the bass. Putting the fifth underneath keeps all the forward pull of the dominant while smoothing the bass movement into the next chord, so C7/G is a common way to voice a V chord without the root jumping around.
C7/G · position 1
C7/G · position 2
C7/G · position 3 · fret 3