This document discusses different types of historical sources that can be used to understand the past. It defines fossils and artifacts as sources that provide clues about early humans since they left little technology behind. Primary sources are accounts created by witnesses, while secondary sources are created later by non-witnesses. Photographs can provide visual historical information but must be properly contextualized to avoid misinterpretation. It profiles several war photographers like Robert Capa who documented major conflicts to convey the human experience and violence of war.