Transformers
Transformers are sometimes used to match the impedances of circuits.
Filters
Filters are frequently used to achieve impedance matching in telecommunications and radio engineering. In general, it is not theoretically possible to achieve perfect impedance matching at all frequencies with a network of discrete components.
L-section
A simple electrical impedance-matching network requires one capacitor and one inductor. One reactance is in parallel with the source (or load), and the other is in series with the load (or source). If a reactance is in parallel with the source, the effective network matches from high to low impedance. The L-section is inherently a narrowband matching network.