Time zones of the Earth
The Earth's surface is divided into 24 zones that stretch along the meridians. Each zone is 15 degrees wide. Local time within one zone differed by exactly one hour from the neighboring zone up or down (in some zones there are exceptions within one state). The time within each zone is the local time for the entire area between the boundaries of the meridians. The countdown is from the Greenwich zero meridian. It is more convenient to analyze all this on the globe. You can tell the time of any place on Earth with a globe. Some globes have a time disc located at the North Pole. The disc is divided into twenty-four equal parts, each representing one hour (or one meridian zone of 15 degrees). Numbering from noon to midnight and from midnight to noon. On globes (not all), half of the disk is shaded dark to indicate night time from sunset to sunrise, and the other half is light in color to indicate daytime hours. By the way, at https://timescanner.pro/ you can find out the exact time in any city.
Suppose you are in Moscow and the time is now 22:00, and you want to know what time it is in Paris, New York. Set the time discs so that the division equal to 22:00 is located directly on the Moscow meridian, this is approximately the 37th eastern meridian. Now rotate the globe along with the time disk (without changing the position of the time disk relative to the globe) until you find Paris. Find the meridian on which Paris is located and look at the time disc and you will see that it is 20.00 in Paris. Find New York on the globe and repeat the procedure. There - 14:00 pm. But here it must be borne in mind that some countries (usually with large territories), artificially by decision of the governments, set their own number of time zones on the territories of their states. So, for example, the territory of Russia extends into almost 12 time zones, if you look along the meridians. But in fact, by decision of the government, 11 time zones were established by administrative division. And in China, for example, there is one time zone for the entire territory of China. In addition, some countries are switching to winter and summer time.