Before you summarize a source in your paper, you should decide what your reader needs to know about that source in order to understand your argument. For example, if you are making an argument about a novel, you should avoid filling pages of your paper with details from the book that will distract or confuse your reader. Instead, you should add details sparingly, going only into the depth that is necessary for your reader to understand and appreciate your argument. Similarly, if you are writing a paper about a non-fiction article, you will need to highlight the most relevant parts of the argument for your reader, but you should not include all of the background information and examples. When you have to decide how much summary to put in a paper, it's a good idea to consult your instructor about whether you are supposed to assume your reader's knowledge of the sources.