Written or spoken words, phrases, or sentences from any source, used without proper documentation.
Summarizing without proper documentation (usually a citation) ideas from another source (unless such information is recognized as common knowledge).
Facts, statistics, graphs, pictorial representations, or phrases without acknowledging the source (unless such information is recognized as common knowledge).
Submitting work simultaneously presented in two courses, unless permission is granted by the both the instructors.
Submitting work, either in whole or in part, created by a professional service and used without attribution (e.g., paper, speech, bibliography, or photograph).
From Deborah Schaeffer, University Library, Cal State Los Angeles
Paraphrasing means putting someone else's idea or statement into your own words. To correctly paraphrase, you will have to cite the source of the original idea or statement.
Below is a great resource on how to paraphrase:
From Purdue University, Online Writing Lab (OWL)