Reference resources - such as encyclopedias and dictionaries - can provide background info on your topic. Reading encyclopedias can also give you search terms to use in the library catalog and databases.
Find hard copy reference books in the library, and online reference resources right here on this page.
Wikipedia can give you quick background for your own knowledge and help you orient yourself to a topic if you know nothing about it
You may get ideas for search terms and key words to use in library tools.
While in most cases professors will not accept a Wikipedia entry as a cited source, the links at the end of it (pointing to sources that editors used) may lead you to citable sources.