In a parallel circuit, all load elements have the same voltage across them. Current has multiple ways to flow through the different branches. Therefore, current flow is less in different parallel parts of the circuit. Here’s how it works.
In a series circuit all load elements are placed one after the other. Current has only one way to flow since there are no branches. Furthermore, current is the same everywhere in the circuit. Voltage, however, will slowly drop in each subsequent element. Here’s how it works.
Ohm’s law is the most fundamental law in all of electronics. It explains the linear relation between current, voltage and resistance in a circuit. These basic building blocks make your circuit do interesting work.
Power is the amount of energy per second that your circuit needs. An electronic circuit releases that energy mostly by doing useful work and generating heat. Fortunately, it’s easy to calculate the amount of energy consumed by your circuit.