Audio CDs are compact discs that contain digital audio files. The discs are used to store music, sound effects, and other audio recordings.
Audio CDs were first introduced in 1982. They were designed to replace the cassette tape as the dominant format for storing and playing back music. The first audio CDs were 12 centimeters in diameter and could store up to 74 minutes of audio.
Today, audio CDs have largely been replaced by digital audio files, which can be stored on portable devices such as smartphones and tablets. However, audio CDs remain popular among collectors and audiophiles.