Linked from
The 9 pages that link to p orbital, each with the reason it gives.
AromaticityRelated: Adjacent p orbitals provide the overlap pathway around an aromatic ring.
Hückel's ruleRelated: Adjacent p orbitals form the continuous π system the rule requires.
Sigma bondRelated: Aligned p orbitals can overlap end-to-end to form sigma bonds.
Bent's ruleRelated: Bent's rule describes how p character is apportioned among bonds.
sp² hybridizationRelated: Two p orbitals mix, while a third can remain unhybridized.