Voltage, otherwise known as electromotive force or EMF, is not actually "power flow" as thought to be by most people. Voltage is potential for "power flow" (actually electrical flow) which is known as current.
Think of voltage as a tightly wound rubber band, or potential energy, that once released becomes current.
It's not the voltage that kills you, it's the current.
E = I x R (where E=volts, I=amperage, and R=resistance). This is Ohm's Law which governs the way in which electricity behaves.
E x I = VA (volt-amps), otherwise known as Watts. A measurement of power.
There are two types of electrical flow, or current. AC and DC. AC is alternating current, this is the type of power in your wall receptacles at home that you plug appliances into. DC is direct current and is used in control circuitry internal to circuit boards, cell phone chargers, and batteries.
The power in your wall, in America at least, is 120 VAC (Volts, Alternative Current) @ 60 hZ (hertz, or cycles per second). That voltage appears as a sine wave. That waves goes up and down (one cycle) sixty times every second. That "up" and "down" is caused by the reversing of the polarity and of the electron flow through the conductor. The electricity literally flows back and forth through the load (appliance, or thing plugged in).
This is all for now.
There are three basic types of circuits.
Series circuit, Parallel circuit, and Series-Parallel circuit.
A series circuit is one in which the current only has one path from L1 (hot) to L2 (common or neutral) potentially through multiple loads.
A parallel circuit one in which there are branches where multiple paths of current flow are allowed simultaneously through multiple loads
A series-parallel circuit is just a combination of these two types of circuits.
The current flow through each load in a series circuit is the same and constant, however, the current flow through each load in a parallel circuit is dependent on the particular resistance (or impedance if a DC circuit) of each individual load, and the current for the "entire" circuit is the sum of each branch added together.
off the top of my head.