Band-pass filter: This type of filter allows only a specific frequency band to pass through while attenuating all other frequencies. It is commonly used in radios and communication systems. 2. Low-pass filters: A low-pass filter allows frequencies below a certain cut-off point to pass through while attenuating higher frequencies. It is commonly used to remove higher-order harmonics. 3. High-pass filter: A high-pass filter allows frequencies above a certain cutoff point to pass through while attenuating lower frequencies. It is commonly used to remove low-frequency noise from signals. 4. Notch filter: A notch filter attenuates a specific frequency or extremely narrow band of frequencies while allowing all others to pass through. It is commonly used in radio frequency interference (RFI) mitigation. 5. Stop-band filter: This type of filter attenuates only a specific frequency band while passing all other frequencies. It is commonly used in applications where unwanted signals need to be removed. 6. Tunable filters: These filters allow the user to adjust the cut-off frequencies of the filtering response according to their needs, making them suitable for various applications such as signal processing and testing.