Active filters are electronic circuits that use active components, such as operational amplifiers, to filter signals. They can amplify or attenuate specific frequency ranges, allowing certain frequencies to pass while blocking others. This makes them useful in various applications, including audio processing and communication systems. Unlike passive filters, which rely solely on resistors, capacitors, and inductors, active filters can provide gain and have better performance characteristics. They can be designed as low-pass, high-pass, band-pass, or band-stop filters, depending on the desired frequency response. This versatility makes active filters essential in modern electronics.