A Passive Filter is an electronic circuit that allows certain frequencies of signals to pass while blocking others. It typically consists of passive components like resistors, capacitors, and inductors, which do not require an external power source to operate. These filters can be used in various applications, such as audio systems and radio communications, to improve signal quality. There are different types of passive filters, including low-pass, high-pass, band-pass, and band-stop filters. Each type serves a specific purpose, such as allowing low frequencies to pass through while attenuating high frequencies, or vice versa. Passive filters are valued for their simplicity and reliability in signal processing.