In suspended chords, the 3rd of the chord is replaced by the 4th degree of the scale it is derived from. Because these chords have no 3rd degree, they work equally well in both major and minor keys. Here are some common suspended chord shapes.
Csus

Gsus

Dsus

Asus

Esus

Suspended chords often resolve back to a major or minor chord of the same letter name, as demonstrated in the next examples. Here are some common suspended progressions to practice with.