I realize that I never explained the difference between infringement and plagiarism. Until more recently, I sort of used to get the two confused myself. Both of them involve not asking permission to use another person's work (in essence, "stealing") but one of them has an even higher level of dishonesty attached to it.
Infringement is when a person reproduces another's copyrighted works without asking permission. The person using the copyrighted work, however, does not purport to own or have created the work.
Plagiarism, a problem that seems to plague academic communities, is when a person reproduces another's works (copyrighted or not) without asking permission, but the person then passes the work off as his or her own. So all those kids who copy-paste passages directly from books into their term papers without properly citing them are plagiarizing. It's like a glorified term for cheating or copying.
Okay, back to your regularly scheduled CopyRighteous.