A compound is said to be aromatic if it satisfies the following three conditions:
(i) It should have a planar structure.
(ii) The π–electrons of the compound are completely delocalized in the ring.
(iii) The total number of π–electrons present in the ring should be equal to (4n + 2), where n = 0, 1, 2 … etc. This is known as Huckel’s rule.