An inductive effect is
an electronic effect due to the polarisation of σ bonds within
a molecule or ion.
This is typically due to an electronegatvity difference between the atoms at either end of the bond.
The more electronegative atom pulls the electrons in the bond towards itself creating some bond polarity for example the O-H and C-Cl bonds in the following examples:
In a simple alkyl carbocation, the positive
C attracts the electrons in the σ bonds connected to that center towards itself and therefore away from
the atom at the other end of the σ bond.
Electrons in C-C bonds
are more readily polarised than those in a C-H bond.
Therefore, alkyl groups are better
at stabilising C+ than H atoms.