Wikipedia ( http://www.wikipedia.org/ ) is an open-content encyclopedia that you can both read and contribute to. This collaborative, open-source resource is one of the largest of its kind. Topics are organized in a variety of ways, including Dewey Decimal, alphabetically, and chronologically. Become an active contributor, or just browse by hitting the “random page” button. Keep in mind, however, that Wikipedia articles are not reviewed by professional fact-checking editors.