take example of conductors in conductors current is due to flow of electrons as electron flows,they suffer collosion due to which they get drifted towards the positive end thus  this  velocity acquired by the electrons is called drift velocity
						

							
take example of conductor in conductor, there are large no of free electrons. current in conductor is due to flow of free electrons
during the flow of free electrons,these electrons suffer a collosion due to collosion they get drifted towards the positive end
thus this velocity accquired by electrons in drifting towards the positive end is called drift velocity
						

							
It is defined as average speed with which free electrons get drifted towards the positive end of the conductor under the influece of an external electric field . Drift speed (velocity) of electrons is given by
  Vd = i/nAe
 where i is the current in amperes
 n is the no. of electrons per unit volume
 A is the area of cross section
 e is the electronic charge
						

							
The potential difference gives electrons a drift ,that is a small constant velocity  along the length of the wire opposite to the electric field.this average velocity of electrons is called as drift velocity of the electons.