RC filters are electronic circuits that use a combination of a resistor (R) and a capacitor (C) to filter signals. They can be designed to allow certain frequencies to pass while blocking others, making them useful in various applications like audio processing and signal conditioning. There are two main types of RC filters: low-pass and high-pass. A low-pass filter allows signals with frequencies lower than a certain cutoff frequency to pass through, while attenuating higher frequencies. Conversely, a high-pass filter does the opposite, allowing higher frequencies to pass and blocking lower ones.