Enantiomers

Two molecules are enantiomers if they are non-superimposable mirror images of each other. In order to have an enantiomer, a molecule must be chiral, that is, cannot have a mirror plane. Enantiomers have identical physical properties except for the direction in which they rotate plane-polarized light. (Note that “enantiomers”  is a relative term between a pair of molecules, just like “fraternal twins” is a relative term between a pair of siblings.)