The point where those electrons enter an electrical circuit is called the "source" of electrons. The point where the electrons leave an electrical circuit is called the "return" or "earth ground". The exit point is called the "return" because electrons always end up at the source when they complete the path of an electrical circuit.
Usually low voltages or DC(Direct Current) is used by the electronic circuits, because load does not need very high power and just a few capacitors, resistors, I.C or other components will not require much power to perform their jobs and it will be powered by a 18650 lithium battery or any other battery source with required voltage and current.
An electric circuit is a path in which electrons from a voltage or current source flow.
Drawings for electronic circuits are called "circuit diagrams". Drawings for electrical circuits are called "wiring diagrams". Like other diagrams, these diagrams are usually drawn by draftsmen, and then printed. Diagrams may also be created digitally using specialized software.