Why should I write an annotated bibliography?
To learn about your topic: Writing an annotated bibliography is excellent preparation for a research project. Just collecting sources for a bibliography is useful, but when you have to write annotations for each source, you're forced to read each source more carefully. You begin to read more critically instead of just collecting information.
To help you formulate a thesis: Every good research paper is an argument. The purpose of research is to state and support a thesis. So a very important part of research is developing a thesis that is debatable, interesting, and current. Writing an annotated bibliography can help you gain a good perspective on what is being said about your topic. By reading and responding to a variety of sources on a topic, you'll start to see what the issues are, what people are arguing about, and you'll then be able to develop your own point of view (OWL at Perdue).
How to Recognize and Find a Scholarly Journal
Thank you to Vanderbilt University's Peabody Library for this excellent video illustrating the differences among scholarly journals and other periodical types.
Primary & Secondary Sources
Primary sources were either created during the time period being studied or were created at a later date by a participant in the events being studied (as in the case of memoirs). They reflect the individual viewpoint of a participant or observer. Primary sources enable the researcher to get as close as possible to what actually happened during an historical event or time period.
A secondary source is a work that interprets or analyzes an historical event or phenomenon. It is generally at least one step removed from the event is often based on primary sources. Examples include: scholarly or popular books and articles, reference books, and textbooks.