MP3 stands for MPEG 1, audio layer 3. MPEG, in turn, is the Moving Pictures Experts Group. This group is an International Organization for Standards (ISO) committee formed to create standards for the coding of moving pictures including moving pictures with audio. One of these standards is MPEG 1. The is the standard "for storage and retrieval of moving pictures and audio on storage media" (Bello, Expert Guide, MPEG Name Game). MPEG 1 consists of three layers. One of these layers is the code for audio. Secure MP3 has a layer of encryption (Bello).
In the past two years, MP3 has become a very popular means of storing and sending audio files on the Internet. This is because their means of copmression offer listeners near CD quality at a low price and relatively samll download time. Web sites have been giving away or selling MP3 files to visitors. Also, there are a wide variety of MP3 players available, many for free. Portable MP3 players are growing in popularity as well. The Diamond Rio Player is the original player, but now many more are being developed and introduced to the market. (Associated Press).
Interest in MP4 seems to be rising. This is MPEG 4 which is the standard for multimedia applications, made official in October of 1998 (Bello, Expert Guide, MPEG Name Game). It is probably an international standard by now. Because MPEG 4 uses the Advanced Audio Coding (AAC) codec sound quality is better and files are smaller (Bello).