The cyclic point groups are the most common classification, especially for biologically active molecules.  The cyclic rotation group is defined by having  only one rotation (C_n) axis.  If no other symmetry operations are present, then the point group is C_n.  If other operations are present, then the molecule can be classified into one of the other three cyclic point groups: S_n, C_nv and C_nh.

• C_n  -  The absence of other symmetry operations puts the molecule in this point group.  These molecules are optically active and polar.  An example is Co(NH₂CH₂CH₂O)₃.
• S_n  -  This group is defined by the absence of mirror planes and the presence of an S_2n.  Examples of this are quite rare.
• C_nv  -  This group is defined by the presence of a s_v, a mirror plane coincident with the C_n.  There will be ns_v's.  These molecules are polar.  An example is ammonia (NH₃).
• C_nh  -  This group is defined by the presence of a s_h, a mirror plane perpendicular to the C_n.  An example is trans-1,2-dichloroethene (CHCl=CHCl).