Planet Earth completes one full rotation of 360° around its axis over the course of 24 hours​. This means that Earth rotates by 15°​ in a single hour. Based on this principle, the planet has been divided into longitudinal time zones. Each of these time zones covers 15°​ of the planet's surface and therefore stands for one hour. Time zones are not always separated by straight lines, because they follow the borders of various nations and regions. Large nations can cover multiple time zones. For example, the Russian Federation is located on 11 different time zones. 

The world time is presented in Greenwich Mean Time (GMT), where the time of noon is determined by the longitude 0 near London. This time zone is also known as Western European time. In Qatar, the time zone used is the third one east of Greenwich. This time zone is known as Arabia Standard Time (GMT [[$ + 3 $]]). When it’s 12:00 in Greenwich, it's 3 p.m in Qatar. The official time is postponed for the summer in several countries by 1 hour. Thanks to the changeover to summer time, more daylight hours will be available. This is more relevant for countries near the equator, where darkness arrives early. 

The advantage of the time zone system is that even if the time in hours differs between time zones, the time in minutes and seconds does not. When moving eastwards from one time zone to the next, the hour hand of the clock must be moved forwards by one hour. When completing a journey around the globe, the clock hand will have moved forwards by 24 hours. However, although the clock shows the correct time, the passenger is one day "ahead" of the time in their destination. Similarly, when moving westwards around the globe, the passenger will be one day "behind" the time of the time in their destination. Because of this, an international date line has been set on the longitude of 180°​. This longitude is located on the other side of the Earth from Greenwich, and it runs through the Pacific Ocean. When traveling over the date line from east to west, the passenger must add one day to their date. Conversely, when traveling over the date line from west to east, the passenger's date will remain the same.