Information Technology Services has created a student page that defines plagiarism, provides examples, and links to the academic integrity statements of a great number of colleges and campuses. If you want much more information on this issue, including faculty guidelines, resources at other institutions, and published articles on plagiarism, check out the Cyberplagiarism: Detection and Prevention site.
Most academic writing is based on the prior work of other people. Copying another person’s work and submitting it as your own is plagiarism, but using someone’s ideas without giving them the appropriate credit is also plagiarism, even if it is unintentional. The University Libraries staff has put together a very nice site that steps you through the process of conducting research, citing your sources, creating references, quoting, and other aspects of the research and writing process. These resources help you to avoid plagiarism.