A low-pass filter is a device or process that allows signals with a frequency lower than a certain cutoff frequency to pass through while attenuating (reducing) the strength of signals with frequencies higher than that cutoff. This is commonly used in audio processing, where it helps to remove unwanted high-frequency noise, making the sound clearer and more pleasant. In electronics, low-pass filters can be found in various applications, such as in speakers and audio equipment. They are also used in signal processing to smooth out data by eliminating rapid fluctuations, allowing for a clearer representation of the underlying trends.