A bandwidth of 20 kHz refers to the range of frequencies that can be transmitted or processed, spanning from 0 Hz to 20,000 Hz. This range is commonly used in audio applications, such as music and voice, where it captures the essential sounds that humans can hear. In telecommunications, a 20 kHz bandwidth allows for the transmission of clear audio signals, making it suitable for telephone calls and radio broadcasts. The wider the bandwidth, the more information can be sent, enhancing the quality of the audio experience for users.