While torsional and steric strain are important in acyclic systems, ring strain (angle) strain becomes important when we force molecus in to cyclic structure.  So the threetypes of strain important in cyclic systems.

1. Torsional strain - destabilization of a molecule upon rotation about a bond.  Torsional strain is a maximum when atoms (typically protons) on adjacent atoms are eclipsed.
2. Steric strain - destabilization of a portion of a molecules because of van der Waals repulsion.  This strain increases as two groups are brought closer together.  
3. Angle strain - the deviation of bond angles of cyclic molecules from typical values expected from VSEPR.

Cyclic systems do not permit the rotations about single bonds.