A linear circuit is a type of electrical circuit in which the parameters or characteristics of the circuit do not change with voltage and current. In other words, the behavior of the circuit remains the same regardless of the voltage or current applied to it.

Explanation:
1. Characteristics of a Linear Circuit:
- A linear circuit exhibits the principle of superposition, which means that the response of the circuit to a sum of multiple inputs is equal to the sum of the individual responses to each input.
- The voltage-current relationship in a linear circuit follows Ohm's Law, which states that the current flowing through a conductor is directly proportional to the voltage applied across it.
- The impedance or resistance of the circuit elements in a linear circuit remains constant regardless of the applied voltage or current.

2. Change in Current:
- In a linear circuit, the parameters or characteristics do not change with a change in current.
- This means that the behavior of the circuit remains the same even if the current flowing through it varies.
- The voltage-current relationship remains linear, and the circuit elements do not exhibit any non-linear behavior such as saturation or distortion.

3. Change in Voltage:
- Similarly, in a linear circuit, the parameters do not change with a change in voltage.
- This implies that the behavior of the circuit remains unchanged even if the voltage applied to it varies.
- The voltage-current relationship remains linear, and the circuit elements do not show any non-linear behavior such as voltage-dependent resistance or capacitance.

4. Non-Linear Circuits:
- In contrast to linear circuits, non-linear circuits exhibit parameter changes with variations in voltage or current.
- Non-linear elements such as diodes, transistors, and amplifiers exhibit non-linear behavior where the voltage or current relationship is not proportional.
- These non-linear circuits are used in various applications such as signal processing, amplification, and modulation.

In conclusion, a linear circuit is one whose parameters do not change with voltage and current. The behavior of the circuit remains the same regardless of the applied voltage or current, following the principles of superposition and Ohm's Law. Non-linear circuits, on the other hand, exhibit changes in parameters with variations in voltage or current and are used for specific applications requiring non-linear behavior.