All the basic principles of this important topic are clearly presented here in an account which takes as examples many compounds of industrial and biological significance. Consideration is given to the structure, reactions, and properties of benzene and classes of aromatic compounds derived from it, and topics such as thermodynamic versus kinetic control and pericyclic reactions are introduced. The text also covers polycyclic arenes and the small and large ring systems which are embraced by the wider definition of aromaticity.