whenever a positively charged body comes near an uncharged body(for eg-a conductor),then it willexrt an attractive force on the free electrons of the uncharged bodydue to which they get concentrated on the surface which is near or in front of the charged body,as a result there is a deficiency of free electrons on the opther surface due to which it acquires some +ve charge....but the net charge on the conductor is zero bcoz no electron has been lost or gained......the charge acquired by the body is only due to polarizatrion....and this charge is known as nuced charge and the process as induction.......hope it helps