An encyclopedia (also spelled encyclopaedia or encyclopædia) is a type of reference work – a compendium holding a summary of information from either all branches of knowledge or a particular branch of knowledge.Encyclopedias are divided into articles or entries, which are usually accessed alphabetically by article name. Encyclopedia entries are longer and more detailed than those in most dictionaries.Generally speaking, unlike dictionary entries, which focus on linguistic information about words, encyclopedia articles focus on factual information to cover the thing or concept for which the article name stands