Hückel's rule

Benzene, the most widely recognized aromatic compound with six delocalized π electrons (4n + 2, for n = 1).

In organic chemistry, Hückel's rule is a rule that help to determine if a molecule has the properties of an aromatic compound. It is named after chemist Erich Hückel, who formulated it in 1931. A well known compound that fulfills the rule is Benzene.