What is Plagiarism?. Plagiarism is the act of copying others\' ideas and/or words and passing them off as one\'s own.Using others\' ideas and words without clearly acknowledging the source of that information is Plagiarism. . What is a Paraphrase?. Express the same message in different words; RewordIt\'s using someone else\'s ideas, but putting them in your own words. Although you use your own words, you still need to acknowledge the source..