History is the study of the past, particularly how it relates to human beingss. 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. Scholars who write about history are called historians. Events that occurred prior to written record are considered prehistory.
History also refers to the academic discipline which uses a narrative to examine and analyze a sequence of events that occurred in the past, and objectively determine the patterns of cause and effect that created them. Historians sometimes 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.
The study of history often focuses on events occurred during particular blocks of time. Historians give these periods of time names in order to allow historians to classify the periods. The names given to a period can vary with geographical location, as can the dates of the start and end of a particular period. The most commonly used periods of time are centuries and decades. Most periods are constructed retrospectively and are based on value judgments made about the past.