Encyclopedias present an overview of a subject in such a way that a nonspecialist can understand it.
Their purpose is to summarize knowledge and to provide a starting point for more extensive research. Entries can range from a short paragraph to articles of several pages with bibliographies at the end. They can be used to look up a particular event or to get information on the highlights of a given period. Because they are usually edited by scholars, they tend to be selective in nature. They often provide good coverage of older works, making them a good complement to computer searches.