A review of recent and current work on microwave filters is presented, and an extensive bibliography of recent articles is appended. The review is largely qualitative and pictorial, rather than mathematical. Among the microwave filter topics discussed are band-pass filters with cascaded lifes or cavities; band-pass and band-stop filters with stubs and parallel-line coupling; low-pass and high-pass filters; the connection between dissipation loss, group delay, and power-handling capacity; delay equalizers; diplexers; directional filters; tunable filters, especially magnetically tunable filters; dielectric-resonator filters; filter techniques applied to semiconductor devices; the connection between filters and directional couplers; filters with open walls; and filters for millimeter waves and higher frequencies.