In order to properly discuss the significance of digital commodities and how they enable online piracy, a brief explanation of what exactly defines a commodity, and from where its value is derived.

 Basically, we make a lot of stuff we don't need. [Source]

A commodity, which exists only capitalist society, is a product that is produced and created for the sole purpose of making a profit - as opposed to using it for personal use. Commodities in the modern era range from things like health care to computers, and high-risk high-return investments to t-shirts. An increasingly globalized capitalist market in the 20th century has radically changed the way business is done in the new millennium, and music, movies and video games are no exception.

One of the ways a commodity's value is determined is through the concept of scarcity, or the ease with which the item can be obtained. Gold, for example, can not be created (it's an element) and can only be recovered from the Earth in ever decreasing numbers, and is one of the major reasons that the price of gold has increased by more than 500% in the last 10 years.

The .MP3 file format has forever changed what music is. It is no longer confined to the the vibrating strings and rushing wind of musicians' instruments, like it was in the 19th century, and it is no longer bound by physical space like a vinyl record or CD like it was for much of the 20th century. Music has, in essence, transcended the 3-dimensional existence that Human beings inhabit, and in so doing have simultaneously duped capitalism's concept of scarcity.

Pretty much the only thing CDs are good for now.

It can be argued that Apple's iTunes store was the most essential force behind this movement, though other organizations such as Napster which provide more or less the same service played key roles. However, because of the rampant success of the iPod, people wanted to fill their shiny new gadgets with music - and they did. Apple is still reaping the benefits, with a 21.87% profit margin and $76.28 billion in 2010.

So music, movies, and entertainment (video games) no longer require physical space to exist. So what?

The "so what" is that they can be copied, quite literally, an infinite number of times, so long as the hard drive space to hold the (very small) files exists (hint: it pretty much does). Torrent files are basically just packages that can contain almost anything - music, video games, movies, and even e-books (the largest of text documents rarely exceed even 5 MegaBytes). Because we've already discussed how easy it is for torrents to spread via swarms, we know why this is a problem for people like the Lars Ulrich and the RIAA. Anybody who buys a few CDs online or in one of the few record stores still in business can put up an entire band's discography in a matter of minutes for quite literally, the entire world.

 Pictured: Pirates.[Source]