00 -03 (dawn)?

03: 00 -06: 00 (dawn)?

06: 00 -09: 00 (early morning)?

09: 00-12: 00 (morning)?

12-15 (noon)?

15-18 (afternoon)?

18 o'clock -2 1 o'clock (at night)?

2 1 -00 (late at night/midnight)

Extended data:

The concept of time refers to some definitions of time system. Include time service system, time zone division and unified time zone system.

Because Beijing is close to meridian 120 degrees, and Beijing is the capital of our country, it is natural to take the local time of east longitude 120 degrees as our standard time. People named it "Beijing time".

Time zones divide the earth's surface into 24 regions according to longitude.

When we see the sun rise in Shanghai, it will take people living in Singapore half an hour to see the sun rise. Residents of London, England are still asleep, and it will take 8 hours to see the sun.

People all over the world, if they use their local time in their life and work, will bring a lot of inconvenience and difficulties to their daily life and transportation. In order to take care of the convenience of use in various regions and facilitate people from other places to take their local conversion of time to other places.

Relevant international conferences decided to divide the earth's surface into regions along the meridian from south to north, and stipulated that the time difference between adjacent regions was 1 hour. People at the eastern and western ends of the same area can see the sunrise within 1 hour at most. When people pass through an area, they will correct the clock to 1 hour (negative to the west 1 hour, positive to the east 1 hour), and when they pass through several areas, they will increase or decrease the hours. This is very convenient to use.

Today, the world is divided into 24 time zones. Because in practice, 1 country or 1 province often spans two or more time zones at the same time, 1 country or 1 province is often grouped together for administrative convenience.

Therefore, the time zone is not strictly divided by the north-south straight line, but by natural conditions. For example, when China has a vast territory, spanning almost five time zones, but actually only the Dongba time zone standard is used, it is based on Beijing time.

References:

Baidu Encyclopedia-Time Concept