"Primary sources are materials produced by people or groups directly involved in the event or topic under consideration, either as participants or as witnesses," (A Pocket Guide to Writing History, 5th ed. Boston: Bedford/St. Martin's, 2007).
These primary sources are what historians, literary and art critics, researchers, etc. rely on to interpret the past, movements, and events. Primary sources differ based on subject. For history they are first hand accounts of an event, topic, or time period. These sources can be diary entries, interviews, laws, ephemeral such as fliers, newspaper articles, photographs, speeches, etc. For literature, primary sources are any original piece that you intend to analyze. Such as poems, novels, biographies, etc. For art, primary sources are any original artistic piece. Such as paintings, sculptures, music, plays, poetry, and any other original form of artistic creation.