Theft always involves a thief taking something away for themselves with the result that the original owner can’t use it anymore. For example, if I steal your bike, you can’t use it anymore. And this is exactly why theft is wrong: you had something which you wanted to use, and now you can’t anymore, simply because I took it.  That’s why downloading music is not theft because it is a form of copying. You download a copy from an original, but the first owner still has the original on his or her computer, and can still enjoy it. In more complicated terms: music files are “non-rival” goods, meaning that my use of the good does not diminish your future use of it. [1]  [1] Investopedia, ‘Rival Good’,