Optical isomerism is a type of stereoisomerism where molecules have the same molecular formula and connectivity but differ in the arrangement of their atoms in three-dimensional space. These isomers, known as enantiomers, are non-superimposable mirror images of each other, much like left and right hands. This property arises from the presence of a chiral center, typically a carbon atom bonded to four different groups. The unique arrangement of atoms in optical isomers affects how they interact with polarized light. One enantiomer will rotate the plane of polarized light in one direction, while the other will rotate it in the opposite direction. This characteristic is crucial in fields like pharmaceuticals, where different enantiomers can have vastly different biological effects.