Active filters are electronic circuits that use active components such as operational amplifiers (op-amps) to implement filtering functions on input signals. Unlike passive filters, which use only resistors, capacitors, and inductors, active filters can provide gain and selectively amplify or attenuate specific frequency components of the input signal. Active filters offer advantages such as adjustable gain, low output impedance, and improved bandwidth compared to passive filters. They are widely used in audio processing, instrumentation, communications, and control systems where precise frequency response and signal conditioning are required.