Kinds of Information -- Background vs. In-Depth

Background information gives a broad overview of a subject. It can also provide definitions, introduce key issues, name specialists in a subject field, identify major dates and events, supply keywords and subject specific vocabulary, and provide bibliographies that lead to additional resources.
Examples: encyclopedias, dictionaries, almanacs

In-Depth information provides detailed data to help you answer your research question.
Examples: journal articles, books, primary sources