The Purpose of Notes

Everyone takes notes for different purposes at different times. Notetaking can serve a variety of functions depending upon both the context in which they are taken (i.e., in lectures or seminars, from books or articles, etc.) and how you want to use them (i.e., to prepare a seminar presentation, write an essay or research paper, revise a topic, etc.).
Generally, however, notes should --provide a summary of the argument --place that argument in a broader context --provide a broad outline of surrounding events or issues --highlight areas which are unclear to you and which you need to follow up further.