The necessary conditions for any system to be aromatic are as follows : -

(i) It should have a planar structure.

(ii) The π–electrons of the compound should be 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 which is known as Huckel’s rule.