Isomers are compounds that have the same molecular formula, but different structural arrangements of atoms. There are various terms that describe different types of isomers. For example, positional isomers have the same functional group but differ in the position of that group on the molecule. Stereoisomers have the same molecular formula and the same connectivity of atoms but differ in the spatial orientation of the atoms in the molecule. Furthermore, enantiomers are a type of stereoisomer that are mirror images of each other and cannot be superimposed. Diastereomers are another type of stereoisomer that are not mirror images of each other and have different physical and chemical properties. Isomers play a vital role in many areas of chemistry, from drug design to material science.