A surround sound system that uses five audio channels plus a subwoofer channel (the "1" in 5.1). Widely used in home theater systems, DVDs are often recorded in 5.1 audio encoding technologies (see Dolby Surround, Dolby Digital and DTS).

The Channels
A 5.1 system provides front left, center and right, surround left and right and subwoofer. A 6.1 system adds a rear center channel, and a 7.1 system provides surround left and right and rear left and right. Following is the typical speaker placement for 5.1, 6.1 and 7.1 channel systems.