Final answer:
A current with charges flowing in a single direction is known as a direct current (DC), which is continuous and unidirectional, distinct from alternating current (AC).
Step-by-step explanation:
A current consisting of charges that flow in one direction only is called a direct current (DC). Direct current is the continuous flow of electric charge in a single direction, which can be seen in constant-voltage circuits, such as those using batteries. The definition of direct current takes its origin from the concept of conventional current, which is the direction that positive charge would move. This approach dates back to Benjamin Franklin who described the motion of charge before the discovery of electrons as carriers of charge in metal wires and the role of ions in solutions, such as salt water.
The fact that direct current represents charge flowing in one direction makes it distinct from alternating current (AC), where the flow of charge periodically reverses direction. In direct current circuits, the same amount of charge that leaves the battery will return to it, indicating charge conservation, and this is true irrespective of whether the charge carriers are positive or negative.