The chronological method of AD is a kind of chronological method which originated from western society and was founded by Christianity in Europe. According to Jesus, the date before Jesus was born is BC, and the date after Jesus was born is called AD. China was the first country in history to commemorate the International Year, which was later introduced to Japan and Viet Nam.
Every decade is called a "decade", for example, 2x years is the twenties, 9x years is the nineties, and so on. But the first twenty years of every hundred years are generally not called "ten years", but the beginning of a century. Every hundred years is called a century, but the first century BC and the first century BC are 99 years, that is, the first year of AD ~ 99 is the first century, the second century is 100 ~ 199, and the first century BC is 99 ~ 1, and so on.
At present, most countries in the world adopt the AD chronology method, and China has been adopting the AD chronology method since the founding of 1949. However, the lunar calendar has not been abolished. Today, traditional festivals in China are based on the lunar calendar.