Overview
In current, the positively charged particles called holes move with the electric field, whereas the negatively charged electrons move against the electric field. It is distinguished from diffusion current (manifested via thermal or density gradients), which results from the random Brownian motion of charge carriers independent of electrical stimulus. If an electric field is applied to an electron existing in a free space, it will accelerate the electron in a straight line from the negative terminal to the positive terminal of the applied voltage. But same thing does not happen in the case of electrons available in good conductors. Good conductors have plenty of free electrons moving randomly in between the fixed positive ion cores. This random movement of electrons in a straight line is known as drift current. Drift current also depends on the mobility of charge carriers in the respective conducting medium.
Read more about this topic: Drift Current