History can be defined in three ways: as past human activities, as a record of past events, and as the process of writing such records. Key elements in studying history include time, place, and culture or civilization. Civilization is characterized by a high standard of living and determinants such as a system of writing, government, and technology. There are two main periods in studying culture - prehistoric, before written language, and historic, after written language developed. Related disciplines include anthropology, which studies human societies and origins, and archaeology, which studies past life through artifacts. Scientific methods used in history include stratigraphic dating based on excavation depth and carbon-14 dating of emissions. Sources include fossils, artifacts,