Paraphrasing is similar to summarizing in that you are reading a source and then integrating it into your paper in your own words. Paraphrasing, however, usually rewrites a small part of a source (such as a passage or paragraph) and provides more than just main ideas. When you paraphrase you are rewriting the passage or paragraph in your own words and providing a connection to you own conclusions.
Paraphrasing can be difficult to do. You need to completely rewrite the passage into your own words. Look at the Types of Plaigaism page of the Plagiarism Research Guide for detailed examples to help you avoid common mistakes.