In digital audio technology, an encoder is a program that converts an audio WAV file into an MP3 file, a highly-compressed sound file that preserves the quality of a CD recording. (The program that gets the sound selection from a CD and stores it as a WAV file on a hard drive is called a ripper.) An MP3 encoder compresses the WAV file so that it is about one-twelfth the size of the original digital sound file. The quality is maintained by an algorithm that optimizes for audio perception, losing data that will not contribute to perception. The program that plays the MP3 file is called a player. Some audio products provide all three programs together as a package.