Hyperconjugation involves overlapping of the following orbitals.

Hyperconjugation involves overlapping of the σ-p -orbitals. It is a general stabilising interaction. It involves delocalisation of σ electrons of C-H bond of an alkyl group directly attached to an atom of unsaturated system or to an atom with an unshared system or to an atom with an unshared p -orbital. The σ electrons of C-H bond of the alkyl group enter into partial conjugation with the attached unsaturated system or with the unshared p -orbital. If is a permanent effect