It is difficult for students to understand how electric circuits function. The processes involved are invisible because they occur at the atomic level and thus are abstract in nature. Electricity can not be felt with using the personal senses (unless we receive an electric which is certainly unwanted), electricity cannot be manipulated directly, and what is happening is thus not readily apparent.
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.
The part of an electrical circuit that is between the electrons starting point and the point where they return to the source is called an electrical circuits "load".
A circuit diagram or wiring diagram uses symbols to represent parts of a circuit.