A primary source is "material that contains firsthand accounts of events and that was created contemporaneous to those events or later recalled by an eyewitness" (Dictionary of Archives Terminology). Letters, diaries, autobiographies, photographs, oral histories, government documents, literary works, speeches, slave narratives, and, in some cases, newspaper articles are just some examples of primary sources.
"Umbra is a digital library that brings together materials documenting African American history and cultural life from archives, libraries, museums, and other US repositories. Umbra features thumbnail images and descriptive information about photographs, manuscripts, documents, books, sound files, video files, and other freely available resources."