History is the analysis and interpretation of the human past that enables us to study continuity and change over time.. It is an act of both investigation and imagination that seeks to explain how people have changed over time. Historians use all forms of evidence to examine, interpret, revisit, and reinterpret the past. These include not just written documents, but also oral communication and objects such as buildings, artifacts, photographs, and paintings. Historians are trained in the methods of discovering and evaluating these sources, and the challenging task of making historical sense out of them. Nevertheless, historians do not always agree on interpretations of the past. The debated differences help expand and enhance our understanding of human development.