Chebyshev filters are a type of analog or digital filter used in signal processing to allow certain frequencies to pass while attenuating others. They are known for their steep roll-off characteristics, which means they can sharply distinguish between the desired and undesired frequency components. This makes them useful in applications where precise frequency selection is crucial. There are two main types of Chebyshev filters: Type I, which has ripple in the passband, and Type II, which has ripple in the stopband. The amount of ripple can be adjusted, allowing for a trade-off between passband flatness and filter sharpness.