Electron flow in only one direction is called direct current (DC).

Here's why:

* Direct current (DC): The flow of electrons in one direction only, from a negative terminal to a positive terminal. This is the type of current produced by batteries and other DC sources.

* Alternating current (AC): The flow of electrons that changes direction periodically. This is the type of current used in most power grids and appliances.

Let me know if you'd like to learn more about DC or AC!