C Suspended 2nd
sus2
0 - 2 - 7Root + major 2nd + perfect 5th
About C Suspended 2nd
Csus2 replaces the E of a C major chord with a D — C, D, G. On guitar it is awkward where the A and D versions are easy, because C major already asks the hand to stretch across three frets, and removing the third does not simplify the shape.
The notes
C, D, G. The D is a major second above the root, and with no third the chord has no mode. Unlike a sus4 it does not lean; it simply sounds open.
The same three notes read from G give Gsus4. That equivalence is more than trivia: a progression can hold the shape and change its meaning by moving the bass.
On the fretboard
The usual voicing frets the third fret of the A string, the open D and G, and the third fret of the B — a shape that has little in common with standard C and has to be learned separately.
In fingerstyle it is often played as a partial with the open G ringing, which is why the chord appears more in arranged pieces than in strummed ones.
Where it shows up
In folk and indie writing in C or G, usually alternating with the plain triad. Held alone it sounds unfinished in a way sus2 chords in more open keys do not.
It also appears in tunings where the open strings supply the second — in those cases the chord is nearly automatic, and its use has more to do with the tuning than with harmony.
The chord is also a reminder that suspension is a matter of context, not spelling. The same three notes called Gsus4 lean hard toward G major; called Csus2 they lean nowhere. Only the bass decides.