 Infinite impulse response

Infinite Impulse Response (IIR) is a type of digital filter used in signal processing. The key characteristic of an IIR filter is that its impulse response (the output when an impulse signal is applied) is infinite in duration, meaning the filter’s output will respond not just for a finite duration but indefinitely. This is typically achieved by using feedback in the filter's structure, which allows the output to depend on both current and past input values, as well as past output values.