You may come across the terms primary sources, secondary sources, and tertiary sources.
Primary sources are original works or research, before it has been commented on, analyzed, or interpreted.
Examples: art, diaries, maps, letters, newspapers, videos and films, photographs, speeches, manuscripts
Secondary sources provide commentary or analysis on primary sources.
Examples: history textbooks, journal and magazine articles that review or provide analysis, books that provide criticism or commentary
Tertiary sources consist of information which is a distillation and collection of primary and secondary sources.
Examples include bibliographies, dictionaries, encyclopedias, and directories.