History, as a discipline, studies and interprets the past in order to arrive at explanations for what past evidence indicates about peoples, events, places, and time periods under consideration.
Historians may study the history of particular groups of people (e.g. women's history or Asian American history), they may study particular events (e.g. history of the Vietnam War or the Crusades), they may study the history of a single country or region (e.g. Pacific Northwest history or Middle East history), or they may confine their interest to a limited time period (e.g. early American history or Medieval history).
Historians take different approaches to their inquiries, and different historians take different approaches to their research and writing. Because individual historians bring different perspectives and different questions to their work, historical interpretations are constantly changing and evolving.