Dolby Digital is a surround sound format offering as many as six distinct sound channels that can place a sound effect anywhere.

The name 5.1 means the system is made up of five full-range channels (front left and right, center, and right and left surrounds) and a channel that just carries bass for use with a subwoofer (the .1 in 5.1). This .1 channel is called the Low Frequency Effects (LFE) channel and adds a sense of realism and depth that makes everything from explosions to music more exciting.