What is aromaticity?

Answer

Those molecules are aromatic which have very high resonance energy. Only those molecules has sufficiently high amount of resonance energy. Only those molecules has sufficiently high amount of resonance energy to become aromatic which
(a) are cyclic
(b) are planar
(c) contains (4n + 2) number of `pi`-electrons in ring.
(d) must have cyclic resonance between (4n + 2) number of `pi-` electrons Where n = 0, 1, 2, 3, 4,....