What n in hukle rule?

In Huckel's rule, "n" refers to the number of π (pi) electrons in a cyclic, planar, and fully conjugated system. According to Huckel's rule, a molecule is considered aromatic and particularly stable if it has 4n + 2 π electrons, where n is a non-negative integer (0, 1, 2, etc.). This rule helps in predicting the aromaticity of various organic compounds. For example, benzene, which has 6 π electrons, fits the rule with n = 1.