I've been able to do all the calculations and whatnot well in my physics class, but I recently stopped to think more about the concept of electricity and how it fundamentally works, but quite frankly I'm a bit stumped and there are some gaping holes in my understanding. Would someone please be able to give me as succinct an explanation as possible to explain some more about electricity? Things such as: - What it is that's actually flowing in a circuit - The difference between charge 'flow' and electron 'flow' - A definition for some different derived SI units: [Voltage, Current, Power, etc.] and so on.. One thing that I don't really understand: - The number of electrons that leave a power source (from the -ve terminal) is the same as the amount that return to the source (through the +ve terminal). If these amounts are the same, and each electron has the same charge (1.6e-19 C), then what is different about the electrons that leave the power source and those that return? What exactly is 'lost'? Thankyou so much to whomever can help me, the textbook definitions that I've come across just present statements without actually explaining the more fundamental concepts of electricity and it's really bugging me.