Use the Oxford Music Online to find background information about topics in music. This can serve as a good introduction to a new topic.
Reference resources are a useful tool to gain basic facts and summary information about a topic. These reference works include articles about music and musicians and historical time periods. There are additional reference resources which are specific to music genres, eras, etc. Browse the 780 section for books related to music. Browse the 900 section for books related to hsitorical and geographical information.