How many GMT time zones exist worldwide?

The concept of GMT (Greenwich Mean Time) time zones is based on the division of the Earth's 360 degrees of longitude into 24 equal segments, with each segment representing one hour of time difference. This results in a total of 24 standard time zones, each one corresponding to a different hour offset from GMT.

In practice, while there may be regions within those time zones that observe different local times due to variations such as Daylight Saving Time or local regulations, the foundational structure of the world’s time system is built around these 24 standard time zones. Each zone is generally centered on multiples of 15 degrees of longitude, as each hour corresponds to 15 degrees of earth rotation (360 degrees divided by 24 hours).

Thus, the correct answer reflects this established structure of time zones distributed globally, confirming that there are indeed 24 principal GMT time zones.