Today, most people on the planet use the modern Gregorian calendar and count the time from the date of the Nativity of Christ. But there are still such calendars that continue to count from, for example, the creation of the world.
Jewish calendar
The date for the beginning of the Jewish calendar is October 7, 3761 BC. These data are responsible for the mythical "creation of the world" or the "era of Adam". Today this calculation is officially used in Israel. Of course, they also use today's calendar, but there are special tables for translating dates.
The Jewish calendar, like the Gregorian, also has 12 months, but there is a difference. The last month in a leap year is doubled, and for this reason the year will be 30 days longer.
According to the Islamic calendar, today is the year 2636. According to the calendar used by the Thais (Buddhist) - 2557, and the Jews - 5769.
Julian calendar
The next calendar is Julian, it starts counting from 45 BC. It was adopted by Julius Caesar. According to this calendar, the New Year began in March and lasted the same as today's Gregorian. In leap years alone, there were 30 days in February. The name of the months originated from the names of the ancient Roman pagan deities. After Octavian Augustus came to power, some changes were made - the year already began in January. The Julian calendar itself was used for more than 1600 years, after which it was replaced by another.
Muslim (islamic) calendar
The Muslim calendar, or "Mohammedan calendar", dates back to 622 AD. - from Hijri - the resettlement of the Prophet Muhammad. This calendar was created by the Arabs and was considered lunar, as a result of which it gained fame in the eastern countries inhabited by Arabs.
As for the basis of the calendar, it is based on the calculation of changes in the lunar phases. In those countries where the main religion is Islam, only the lunar calendar is used, which does not depend on the movement of the sun. By the way, this attitude to calculus is dictated by religious tradition, because it is no coincidence that even breaking the fast after fasting is customary at night.
Chinese calendar
The main beginnings and the appearance of the first foundations of the calendar in China date back to the III millennium BC. The Chinese calendar has two types: solar-lunar and solar.
After the 1911 revolution, China switched to the Gregorian calendar.
Both types of calendars are cyclical, they do not have months, only numbers of days and cycles.
Today, modern China continues to use the lunar calendar to clarify the dates of festivities such as the "Spring Festival", or (another name for) the Chinese New Year, which, as you know, does not have a fixed date and is shifted by almost a day every year. The lunar calendar also calculates the day for the Mid-Autumn Festival and other traditional celebrations. In addition, the Chinese also use the Gregorian calendar, which is considered their standard.
