Turnitin.com is a service schools can use to detect plagiarism. Students submit their papers to turnitin.com, in MS Word format, I guess, and it analyses the text for plagiarism. Here's how the company describes it:
The industry's most advanced search technology that checks papers against our in-house copies of both current and archived internet content and our proprietary database of millions of previously submitted student papers.
My Economics professor told us an amusing story this morning about turnitin.com. She is on a committee that was evaluating using the service. Going through a demo of the service while on the phone with a rep from the company, she asked what happens if the student hides nonsensical characters within the text by replacing whitespace with characters in a white font. She went ahead and tried it with the sample plagiarized poem the company provided. Lo and behold, the poem was reported as not being plagiarized. Despite one professor's continued desire to use this $5,000 service, the committee opted not to.
The state is that great fiction by which everyone tries to live at the expense of everyone else. - Frederic Bastiat