Isomers are molecules that have the same molecular formula (same number of each type of atom) but different structural arrangements. These different arrangements can lead to significantly different properties.

Here are some examples of types of isomerism:

* Structural Isomers: These have the same molecular formula but differ in the way the atoms are connected. For example, butane and isobutane both have the formula C4H10, but butane has a straight chain structure while isobutane has a branched structure.

* Geometric Isomers: These have the same molecular formula and connectivity but differ in the spatial arrangement of atoms around a double bond or a ring. For example, cis-2-butene and trans-2-butene both have the formula C4H8, but the methyl groups are on the same side of the double bond in cis-2-butene and on opposite sides in trans-2-butene.

* Enantiomers: These are stereoisomers that are mirror images of each other and cannot be superimposed. They often have different biological activities. For example, the drug thalidomide has two enantiomers, one of which is effective in treating morning sickness while the other is teratogenic (causing birth defects).

Carbon's ability to form multiple bonds and its tetrahedral geometry allows for a vast diversity of possible arrangements, leading to a huge number of isomers. This is one of the reasons why carbon is the backbone of life and forms the basis for so many different organic molecules.