History (from Greek ἱστορία, historia, meaning "inquiry; knowledge acquired by investigation") is the scientific study of the past. Events occurring before the invention of writing systems are considered prehistory. "History" is an umbrella term that relates to past events as well as the memory, discovery, collection, organization, presentation, and interpretation of information about these events. Historians place the past in context using historical sources such as written documents, oral accounts, ecological markers, and material objects including art and artifacts.
History also includes the academic discipline which uses narrative to describe, examine, question, and analyze a sequence of past events, and investigate the patterns of cause and effect that are related to them. Historians seek to understand and represent the past through narratives. They often debate which narrative best explains an event, as well as the significance of different causes and effects. Historians also debate the nature of history and its usefulness by discussing the study of the discipline as an end in itself and as a way of providing "perspective" on the problems of the present.