The best sound we can get in our home is not from records or even tapes, but from compact discs. These small silvery discs are only 11 cm in diameter, but may contain more than an hour’s music on just one side. They need a special player which contains a laser and computer, and give superb sound without any background hiss or crackless. The reason that compact discs are so good is that the sound is digital. This means that it is recorded on the disc in the form of computer codes which reproduce the recorded sound very accurately.