An analog filter is an electronic circuit that processes continuous signals to allow certain frequencies to pass while attenuating others. These filters can be categorized into types such as low-pass, high-pass, band-pass, and band-stop, depending on the frequency range they target. They are commonly used in audio processing, radio communications, and signal conditioning. Analog filters are typically made using passive components like resistors, capacitors, and inductors, or active components like operational amplifiers. Unlike digital filters, which work with discrete signals, analog filters operate in real-time, making them suitable for applications where immediate response is crucial.