Isomers are molecules that have the same chemical formula but different structures or arrangements of atoms. This means they contain the same number of each type of atom, but the way these atoms are connected or arranged in space varies. Isomers can exhibit different physical and chemical properties, making them important in fields like chemistry and pharmacology. There are two main types of isomers: structural isomers and stereoisomers. Structural isomers differ in the connectivity of their atoms, while stereoisomers have the same connectivity but differ in the spatial arrangement of their atoms. Understanding isomers is crucial for studying the behavior of various compounds.