Why does the time change when you travel?

The time changes when you travel due to the Earth's rotation and its division into time zones, which are typically set at one-hour intervals based on longitudinal lines. As you move east or west across these zones, local time adjusts to reflect the position of the sun in the sky. Additionally, factors like Daylight Saving Time can further alter local time, leading to variations even within the same time zone. This system helps standardize timekeeping for social, economic, and navigational purposes.