Enantiomers are a type of stereoisomer that are mirror images of each other but cannot be superimposed. They have the same molecular formula and connectivity of atoms, but differ in the spatial arrangement of their atoms. This property is crucial in fields like pharmaceuticals, where one enantiomer may have beneficial effects while the other could be harmful. These compounds often exhibit different optical activities, meaning they rotate plane-polarized light in opposite directions. One enantiomer is referred to as the R form, while the other is the S form, based on the Cahn-Ingold-Prelog priority rules. Understanding enantiomers is essential in chemistry and biochemistry.