"An electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, voltage sources, current sources and switches. An electrical circuit is a network consisting of a closed loop, giving a return path for the current." in WikipediaThe two simplest of these circuits are called series and parallel and occur very frequently.
In the image (above) we can see the schemes of two simple electric circuits. The first circuit (fig. 1) the lamps are connecting in a series circuit. The second circuit (fig. 2) we have the lamps are connecting in a parallel circuit.
You can try to build both circuits by using a PhET simulation. Try to do it by clicking the image bellow.