Definition of Hyperconjugation
Hyperconjugation is a stabilizing interaction and this interaction results due to the electrons that are present in σ (sigma) bond with the nearby empty, half, or partially filled π-orbital. This interaction between the electrons is responsible to give an extended molecular orbital and therefore, the stability of the system is increased.
According to Valence Bond Theory (VBT), it can be described as double bond no bond resonance. Hyperconjugation is one factor that makes us understand that when the number of substituents of alkyl present on the carbocation increases, it leads to the increased stability of the molecule. The orbital interaction keeps the electron being in the orbital having the lowest energy.