Plagiarism is the use of someone else's words, ideas, or line of thought without acknowledgement. Even when plagiarism is inadvertent - the result of careless note taking, punctuating, or documenting - the writer is still at fault for dishonest work, and the paper will be unacceptable. To avoid plagiarizing, learn to recognize distinctive content and expression in source materials and to take accurate, carefully punctuated, and documented notes.
Perrin, Robert. The Beacon Handbook and Desk Reference.Boston: Houghton Mifflin Company, 2000.