Electric current is defined as the rate at which electric charge flows.

Ampere is the SI unit for electric current (A)

Hence, Electric current  

I = Q$/$t = charge$/$time

The conventional current flows in the same direction as positive charges, from greater potential (positive) to lower potential (negative) (negative).

Electric current is caused by electrons moving from a lower potential (negative) to a higher potential (positive), hence the direction of electric current is the polar opposite of conventional current.Let's not forget that its more of a convention.