1. Circuit. A conducting path through which an electric current either flows or is intended to flow is called a circuit. The various elements of an electric circuit are called parameters (e.g. resistance, inductance and capacitance). These parameters may be distributed or lumped.
2. Linear circuit. The circuit whose parameters are constant (i.e. they do not change with voltage or current) is called a linear circuit.
3. Non-linearcircuit. The circuit whose parameters change with voltage or current is called a non-linear circuit.
4. Unilateral circuit. A unilateral circuit is one whose properties or characteristics change with the direction of its operation (e.g. diode rectifier):
5. Bilateral circuit. It is that circuit whose properties or characteristics are same in either direction (e.g. transmission line).
6. Electric network. An electric network arises when a number of parameters or electric elements coexist or combine in any manner or arrangement.
7. Active network. An active network is one which contains one or more than one sources of e.m.f
8. Passive network. A passive network is one which does not contain any source of e.m.f.
9. Node. A node is a junction in a circuit where two or more circuit elements are connected together.
10. Branch. The part of a network which lies between two junctions is called branch.