Benzene was considered as parent ‘aromatic’ compound. Now, the name is applied to all the ring systems whether or not having benzene ring, possessing following characteristics.
(ii) Complete delocalisation of the π electrons in the ring
(iii) Presence of (4n + 2) π electrons in the ring where n is an integer (n = 0, 1, 2, . . .).
This is often referred to as Hückel Rule.
Some examples of aromatic compounds are given below: