From the early 1990s, as Internet usage first began to proliferate, users quickly saw the potential for sharing music. But a combination of basic connection speeds and large file sizes made uploading and downloading a painfully slow process. As early as 1987, Germany's prestigious Fraunhofer Institute had been engaged in researching high-quality, low bit-rate audio coding: in short, how an audio file can be compressed in size without affecting its sound quality. The format they came up with in 1989 was called MPEG (Moving Picture Experts Group) Audio Layer III, or MP3.
MP3 compression is a simple concept to understand—even if the process itself is highly complex. A compact disc (CD) stores its information digitally, in binary digits (bits); every second of stereo music contained on a CD consists of 1,411,200 bits. MP3 compression reduces the number of bits in a recording by taking out "unnecessary" information. It does this by using "perceptual noise shaping"; characteristics of the human ear are taken into account in its compression algorithm.
So, for example, certain sounds that cannot be heard by the human ear, or are masked by other louder sounds, may be removed without significantly altering the overall sound. In fact, compressing a song "ripped" from a CD can typically reduce its size by a factor of 12—the MP3 version of the song can therefore be downloaded twelve times more quickly than the uncompressed version.
The speed at which files could be transferred immediately made MP3 the format of choice for moving digital music around on the Internet and spawned a whole new phenomenon: the downloading of music—legal or otherwise.
