An electrical circuit has numbers of nodes. If one starts from one node and after going through a set of nodes returns to same starting node without crossing any of the intermediate node twice, he has travels through one loop of the circuit.

Any of the circuit element when connected to the circuit, it is definitely connected between two nodes of the circuit. When an element exists between two nodes, the path from one node to another through this element is called branch of the circuit.

The point through which an circuit element is connected to the circuit is called node.