Audio CDs, or Compact Discs, are a digital format for storing and playing music. They were first introduced in the early 1980s and quickly became popular for their ability to provide high-quality sound. Each CD can hold about 74 to 80 minutes of audio, allowing for multiple songs or an entire album to be stored on a single disc. To play an audio CD, you need a CD player, which reads the data encoded on the disc using a laser. The sound is then converted into analog signals that can be amplified and played through speakers. Audio CDs are still used today, although digital streaming has become more common.