TurnItIn  

From the TurnItIn FAQ:

"Turnitin provides originality checking, online grading and peer review to prevent plagiarism prevention and engage students in the writing process. Turnitin encourages best practices for using and citing other people's written material and offers instructors ways to save time and improve their feedback on the writing process. The service offers a complete web-based service to manage the process of submitting and tracking papers electronically, providing better – and faster – feedback to students."

This guide will walk you through the ins-and-outs of using TurnItIn outside of MyCourses.  

For more information using TurnItIn in myCourses, contact Online Learning at:

Email: online@rit.edu
Phone: 475-5089.

Faculty Information

• Creating an Account
• Adding Classes and Assignments
• Submitting Papers

Student Information

• Creating an Account

Each time a paper is submitted to TurnItIn, an Originality Report is created that compares that document with the TurnItIn database, along with a number in the form of a percentage, called the Similarity Index.  These are tools to be used to identify when matching text has been found, ideally to ensure proper citations.  As mentioned on TurnItIn's website:

"Warning:  These indicies in no way reflect TurnItIn's assessment of whether a paper contains plagarized material or improperly used material."

So, if you were running an originality report on this guide, you would probably find a decent chunk of matching text.  Just remember:  cite your sources.

Source:  http://turnitin.com/en_us/training/student-training/about-originalitycheck