what is the international date line

The International Date Line is an imaginary line on Earth's surface that serves as the boundary where each calendar day starts. It is located at about 180° east or west and runs from the North Pole to the South Pole, roughly following the 180.0° line of longitude and deviating to pass around some territories and political borders. When you cross the date line traveling east, you subtract a day, and if you cross the line traveling west, you add a day. The date line is not defined by international law and has no legal international status. It is also not straight but curves around landmasses and national borders.