Let me explain an electrical science example to demonstrate. We are all aware that maximum power can be transmitted through an external load in a circuit when the internal resistance of the source is equal to the resistance of the external load. The concept of "resistance matching" for optimal power transmission is expanded to "impedance matching" when working in the frequency domain and incorporating capacitors and inductors into our circuits, where impedance is effectively a complex-valued resistance. The maximum power transfer point in these circumstances occurs when the source impedance and the load impedance are complex conjugates.
Impedance matching in electronics is the process of designing or modifying an electrical device's input impedance or output impedance to a desired value. The target value is frequently chosen to increase power transfer or decrease signal reflection. Impedance matching, for instance, is frequently used to enhance power transfer from a radio transmitter through the connecting transmission line to the antenna. If the transmission line is terminated with a matching impedance, signals will be transmitted on the line without reflections.
Transformers, tunable networks of lumped resistance, capacitance, and inductance, or suitably sized transmission lines are a few methods of impedance matching. Over a given frequency band, practical impedance-matching devices will typically yield the greatest results.
Although widely used in electrical engineering, the idea of impedance matching is also important in other fields where energy other than electrical is exchanged between a source and a load, such as acoustics or optics.