Internationally, the birth of Jesus Christ is the starting point. Before the birth of Jesus Christ, it was called BC, and the birth of Jesus Christ began in AD. This period was probably when the Western Han Dynasty in China was handed over to New China. AD: The year when Jesus Christ was born was the beginning of the era in Europe and America, which was adopted by many countries all over the world, so it was called AD ... also known as "AD". AD: The method of chronology in western countries began in the year when Jesus was born, so it is called AD. Also known as "AD".

The year when the legendary Jesus Christ was born is considered as the first year of the year. From the 6th century to the10th century, it gradually became the universal era of Christian countries, so it was originally called the "Christian era". Later, it was used by most countries in the world, so it was renamed "A.D.", which is often expressed in A.D. (the abbreviation of Annodomeni means "the year of the Lord").

In history books, the year before the birth of Jesus is called "BC", which is often written as BC (BC), meaning "before Christ"; The year after the birth of Jesus is "After A.D." or "A.D." for short. The first year of AD is equivalent to the first year of China Xihanzi Yuan. ?

The word "century" comes from Latin, meaning that 100 is also counted from the year when Jesus was born: from the first year of BC to 100 is the first century, and from 10 1 200 is the second century. By analogy, it is the 20th century, and 200 1 year is 2 1 century. The year of A.D., also known as A.D., is called "A.D." or "A.D." for short. The AD calendar is the Christian calendar. The Latin word of the Middle Ages is Anno Domini, abbreviated as AD, which means "in the year of the Lord".