In the context of timekeeping and chronology, an epoch refers to a specific point in time that serves as a reference or starting point for a subsequent system of measuring time. For example, the Unix epoch starts from January 1, 1970, and is used in computing to represent time as the number of seconds that have elapsed since this date, not counting leap seconds. In a broader historical or geological sense, an epoch can signify a distinctive period characterized by particular circumstances, events, or cultural themes. For example, the Holocene epoch in geology marks the last 11,700 years of Earth's history, a time during which human civilizations have arisen. Therefore, the term "epoch" can be used in multiple contexts but generally denotes a foundational or transitional moment that leads to a new state of affairs or understanding.