The process of acquiring a song from an Internet source and placing it in your personal computer is the definition of "downloading music." There are legal and illegal ways to download music, but the actual process of receiving the media music file onto your computer is always the same.

Downloading

A song takes about a minute to download on most modern computers. But if an internet connection is disrupted, the download with be terminated. Most music is downloaded in mp3 format.

Illegal Downloads

Downloading a song from a source that does not have permission to release the song is considered an illegal download. Any downloaded music that hasn't been paid for is considered "pirated."

Purchased Downloads

Sites like Lala.com, Emusic.com and iTunes sell mp3s downloads of music. These can be purchased online with a credit card, but should be only used for personal use. Copying a purchased mp3 and selling or giving it to someone else is illegal.

Uploads

An upload is simply the act of making something available to download. So if you were to upload a song onto an online source, other people on the Internet can then download it to their computers. But upload with caution because this can also be illegal if you don't have permission from the owner of the music.

Playing Downloaded Music

Downloaded music cannot be listened to without digital music playing software. And it cannot be listened to until the download has completed. Programs like iTunes and Winamp enable you to listen to mp3s on your computer. The music can also be moved to an external media player.

Source:

What is Downloading?

Resource:

iTunes Download