IIR filter (Infinite Impulse Response)

An IIR (Infinite Impulse Response) filter is a type of digital filter used in signal processing to modify or analyze signals. It processes input signals by combining current and past input values along with previous output values, allowing it to produce a desired output efficiently. Because of its feedback mechanism, an IIR filter's response can be thought of as theoretically lasting indefinitely, which is why it’s called "infinite." This makes IIR filters capable of achieving sharp filtering effects with fewer computing resources, making them popular in audio, communications, and control systems.