Millions have enjoyed recorded music since 1877 when Thomas Edison invented the phonograph. Then came radio, records, tapes and CD's. But today's digital audio players are a quantum leap forward in music technology. To understand what makes these music players so revolutionary, let's explore the question, "How do mp3 players work?"

Until recently listening to music recordings involved mechanically moving the media past an interface to pick up an analog signal called a wave-form. This signal of vibrations was amplified and sent to the speakers where we heard it as sounds. When digitized, the wave-form becomes a WAV file. It's a major improvement, but the file is very large and a CD disc is limited to about 80 minutes of music.

So What is an iPod, and How does an iPod work?

Apple's iPod is the best known mp3 player. In answer to the question, How do iPods work, the next two paragraphs really describe how all portable digital music players function.

Software converts the music to a small digital file, usually WAV to mp3, using a codec like MP3 or WMA. The codec compresses the file by discarding sounds inaudible to the human ear. The digital file is stored in the mp3 player's flash or micro-drive memory. Because the file is so small, a player no larger than a deck of cards can hold up to thousands of songs.

For play-back the mp3 player executes several functions. Embedded software reads the file, decompresses the encoding, converts it back to analog, amplifies the signal and sends it to the headphones. And voil