The C minor chord is a 3-note chord consisting of the notes C, Eb and G.
You can see these notes highlighted in the interactive piano chart below.
The chord itself is often abbreviated as Cm.
Chords that are a superset of Cm. The chords include more notes but always C, Eb and G.
Chords that are a subset of Cm. These contain less notes but all of them are included in Cm.
In case you prefer a non-interactive variant of the chord chart, we've embedded a PNG image below that shows the notes for the the Cm chord. Feel free to save or share the image as needed.