The term “visual material” refers to any primary source in which images, instead of or in conjunction with words and/or sounds, are used to convey meaning. Some common and useful types of visual materials are as follows:

• Original art, including but not limited to paintings, drawings, sculpture, architectural drawings and plans, and monoprints.
• Prints, which are works produced in multiple but limited numbers such as woodcuts, engravings, etchings, and lithographs
• Graphic arts, including materials such as posters, trade cards, and computer generated graphics
• Photographs
• Film and video

Any of these materials can provide valuable information to a researcher. Factual information can often be extracted from visual materials; however, the best information imparted by these materials is often of a subjective nature, providing insight into how people see themselves and the world in which they exist.

• Secondary sources interpret and analyze primary sources. Because they are often written significantly after events by parties not directly involved but who have special expertise, they may provide historical context or critical perspectives. Secondary sources routinely include pictures, quotes or graphics of primary sources and can include scholarly works, textbooks, newspaper, journal articles and biographies.  
• Tertiary sources or reference sources summarize and synthesize information about a topic from other sources. Tertiary sources can be a useful tool for locating primary and secondary sources. Examples of tertiary sources include encyclopedias and dictionaries, chronologies, almanacs and bibliographies.