A format introduced several years ago by Sony that allows recording and playback of audio to and from a small magneto optical disc with a capacity of 140MB. To be able to record 74 minutes of music, the technology applies a data compression algorithm called ATRAC that compresses the data by about 5:1, but also permanently changes the file on decompression. Therefore it is know as "lossy" algorithm. However, the advantages are a very compact size, a claI'm of 1,000,000 reuses of the media and the ability to random access data on the disc.