As people, we like to talk about our opinions, share ideas, and pass on things that we like. We share symbols, icons, discourse, words, pictures, music, philosophies. We suggest books, review films. These days, we often share media in a much more direct way.
Sharing is often deeply personal. In many cases, what we share represents us - you can find a bit of media that says what you'd like to say, and says it better. You can project an identity, showing others your good taste and the kinds of things you like.
Recently, the concept of memes has been come into being; the idea of infectious ideas that spread from person to person. It's an appealing concept. A large part of the idea is that that concepts can act like living things, using us as a platform for carrying on their existence, and subject to natural selection. Which is pretty interesting-sounding.
It's also utter bullshit. We share naturally; special and virulent ideas are a fun way to talk about it, but the interesting thing is us. Referring to things in a anthropomorphized way? That's also very much us. Information doesn't want to be free; it doesn't have a tendency to spread - we have a tendency to spread it. We pick up language and concepts as tools (and how we love our tools). On a basic level, simple communication, it costs us nothing to hand them about; they can be duplicated without loss.
This drive to share such stuff doesn't come without some problems, once it gets out into the world. The world includes musicians who are already trying to work with a problematic system supposedly set up to repay them for their work. Pharmaceutical companies spend millions on research to get the first pill of a type - but the pills cost pennies afterwards, and can be made by everyone. Our methods in such cases, as well as our laws, have not caught up with out basic tendencies and present technology.
Sharing the thoughts of others remains our highest compliment to their work. But the structures we work in can make that compliment into an offense.