Encyclopedias, dictionaries, and other reference resources help you to discover basic information—names, dates, definitions, summaries, etc. These are good places to start when beginning research on an unfamiliar subject, and when choosing or narrowing a paper topic.
Reading a literary work set in an unfamiliar time period or location? Reference works can help provide a brief introduction to countries, their history, and even to specific historical events. Knowing its context can bring an added layer of meaning to a literary work.