The infeasible method of AD chronology begins with the so-called year of Jesus' birth. The year before this year is called the year of BC, and the year after this year is called the year of AD. However, it should be noted that there is no zero year. China adopts 1949 calendar year after the establishment of People's Republic of China (PRC). Today is 2007.

The origin of advertising calendar

A. D. is the abbreviation of "Gregorian calendar era", which is an international calendar system. The legendary birth year of Jesus Christ is the first year of Gregorian calendar (equivalent to the first year of Emperor Ping of the Western Han Dynasty in China).

AD is often represented by a.d. (Latin abbreviation of Anno Domini, meaning "the year when the Lord was born"), while BC is represented by b.c. (abbreviation before Christ, meaning "before Christ").

This chronological system began to be adopted by European countries. China adopted the Gregorian calendar month and day (19 12) one year after the Revolution of 1911, but at the same time adopted the year of the Republic of China.

The calendar year of People's Republic of China (PRC) adopts the calendar year system of most countries in the world, which was decided at the first plenary session of China People's Political Consultative Conference in September 1949. At the meeting, everyone agreed to adopt the common calendar system in most countries in the modern world, that is, adopt AD as the calendar year of new China. On September 27th, the second of the four resolutions adopted at the first plenary session of the China People's Political Consultative Conference was: "The year number of People's Republic of China (PRC) adopts AD".

There are many dating methods in the world, but at present the most commonly used method in the world is the AD dating method. In addition, there are chronologies of cadres and branches, astronomical chronologies, historical chronologies, and chronologies of emperors' titles. In addition, there are Islamic times, Buddhist times, Jewish times, Greek times, Japanese times and so on.

In China, as early as 2000 BC, it had its own calendar. For a long period of history, China adopted the "era method of cadres and branches", that is, the ten-day cadres and the twelve-day branches were combined into one, and every 60 years was a cycle.

Because the starting point of the AD calendar is 1, there is no "AD 0", so most scientists who have a full understanding of the AD calendar and the most authoritative astronomical institutions in the world clearly support the statement that 2 1 century began at 200 1.