A "perfect" time zone is defined as 15 degrees longitude. At the equator, one degree of longitude is 69 miles (111 kilometers) broad, diminishing to zero at the poles. So, in the equator, a "ideal" time zone is approximately 1035 miles (or 1665 kilometers) broad. The actual width of standard time zones varies from 976 miles to 1244 miles.
Time zone boundaries are usually determined by the location of major cities. Thus, a time zone may include portions of more than one country. For example, most of North America and much of Europe are included in the same time zone: GMT-5. However, during World War I and World War II, the British imposed large areas of daylight saving time on their colonies and allies. These areas include Africa, Asia, Australia, and parts of Latin America and South America.
Daylight saving time was made legal in the United States during World War I when electricity was needed for weapons development. The idea caught on quickly, and by the start of World War II, almost all U.S. cities followed suit. Today, over half the countries in the world use some form of daylight saving time. Although its origins are military, today's version of daylight saving time has nothing to do with war or energy conservation; instead, it allows us to expand our hours of sunlight while reducing our dependence on artificial light.
That's not quite correct. Most time zones are around one hour apart (i.e., 15 degrees). However, for political reasons, their limits do not perfectly follow longitude lines (in the US, for example, they tend to follow state boundaries). So sometimes there are two or more adjacent time zones on either side of a region that uses a different standard time. In this case, their borders will not be aligned with longitudes.
There are exactly 24 hours in a day. If it was any other way, something would have to give! The number of minutes in an hour is 60. The number of seconds in a minute is 60x1=60. The number of milliseconds in a second is 1000x1=1000.
Since there are only 24 hours in a day, every year we use up nearly all of them. We need more hours in a day. But how many? Well, it depends on what you want to do with your life! If you want to play sports or go to school, then you need more hours in a day. If you just want to sit around and watch TV, then you might be happy with less than 24 hours per day. The important thing is that you should figure out what you want to do with your life and work toward achieving that goal. Then you will know how many hours to spend each day.
15 degrees equals one time zone, therefore every 15 degrees of longitude equals one time zone. The term "time zone" comes from the fact that during World War I, the British government set up an office called the Office of Time Administration that published maps showing how to tell time across the country. These maps were called "zones" because they divided the world into zones using lines of longitude.
Time zones were originally established by the British as part to the war effort, but today they are used by countries for their own administrative purposes. A country's capital city is usually in a single time zone, while other large cities may be separated from it by multiple time zones.
In North America, time zones are divided into Eastern and Western. In Europe, there are two different systems in use: Central European Time (CET), which is based on Greenwich Mean Time (GMT), and Eastern European Time (EET), which is three hours ahead of GMT. Israel and most of Asia use UTC+03:00. Africa is split between UTC+02:00 in the north and south. In the southern part of Africa is where South Africa is located, which uses UTC+01:00.