Aromatic compounds are those that meet the following criteria: (i) The structure must be cyclic, containing conjugated system. (ii) Each atom in the ring must have an unhybridized p orbital. (The ring atoms are usually sp2 hybridised ) (iii) The unhybridised p orbitals must overlap to form a continuous ring of parallel orbitals. In most cases, the structure must be planar (or nearly planar) for effective overlap to occur. (iv) Delocalization of the π electrons over the ring must lower the electronic energy. An antiaromatic compound is one that meets the first three criteria, but delocalization of the π electrons over the ring increases the electronic energy.

Aromatic compounds are those that meet the following criteria:
(i)   The structure must be cyclic, containing conjugated system.
(ii)   Each atom in the ring must have an unhybridized p orbital. (The ring atoms are usually sp² hybridised )
(iii)   The unhybridised p orbitals must overlap to form a continuous ring of parallel orbitals. In most cases, the structure must be planar (or nearly planar) for effective overlap to occur.
(iv)   Delocalization of the π electrons over the ring must lower the electronic energy.
An antiaromatic compound is one that meets the first three criteria, but delocalization of the π electrons over the ring increases the electronic energy.