In many cases, you'll want to learn some background information about a particular art movement, an artist, or a piece. Wikipedia can be a great source of background information, but did you know that there are encyclopedias specifically dedicated to art? Many of these are available online, only from the library.
Use these sources to learn more about the history of a person, piece, or movement, and even to give you some ideas about what you might want to explore in more depth.
Oxford Art Online is the access point for Grove Art Online, the Benezit Dictionary of Artists, and other Oxford art reference resources. It includes the entire 34 volumes of The Dictionary of Art, with articles as well as links to images on gallery and museum web pages around the world. Includes biographies of artists and searchable images.