Encoders are software programs that are used for compressing information. Often, the function of an encoder will also allow for the conversion of data from one format to another. While there are several types of programs that accomplish this for text data, the encoder is usually associated with audio and video.

One of the common uses of an encoder today has to do with the conversion of audio files from an originating format to one that will match with a specific player. For example, an encoder would be used to compress and convert a WAV file into a file type that would be compatible on an MP3 player. The WAV file would be compressed to a fraction of the original size. The compression would take place without having a negative impact on the sound quality of the converted file.

Maintaining sound quality while significantly reducing the size of the original file is central to how the encoder accomplishes the task. The idea is to maintain the integrity of the code while still creating the proper encrypting codes that are relevant to the new format. In some cases, this may involve adding redundancies to the converted file. At other times, the encoder may minimize redundancy. The exact setup of the original file will dictate what has to be done in order to compress and convert the audio or video file.

The encoder can also help bridge the gap between older technology and the latest in portable handheld devices that store music and files. Inherent to the function of devices that allow music files to be created from vinyl records is the presence of an encoder. In this application, the encoder helps to convert the older analog signal of the vinyl recordings into a bitstream and file format that can be loaded onto a CD or stored on a computer. If necessary, the newly created audio file can once again be converted into another digital format and loaded onto a handheld device.