Q: How does one count the years?
A: The Islamic calendar (or Hijri calendar) is a lunar calendar. It contains 12 months that are based on the motion of the moon, and because 12 lunar months is 12 x 29.53=354.36 days, the Islamic calendar is consistently shorter (11 Days) than a solar year, and therefore it shifts with respect to the Gregorian calendar. The Islamic calendar is the official calendar in countries around the Gulf, especially Saudi Arabia. But other Muslim countries use the Gregorian calendar for civil purposes and turn to the Islamic calendar for religious purposes.
The order of the Islamic calendar begins with Muharram, Safar, Rabi-al- Awwal, Rabi “al- Thani, Jumada al-Awwal, Jumada al-Thani, Rajab, Sha’ban, Ramadan, Shawwal, Dhu al-Qi’dah and Dhu al-Hijjah. [Quran – 9.36] Surely the number of months with Allah is twelve months in Allah’s ordinance since the day when He created the heavens and the earth. Each month starts when the lunar crescent is first seen after a new moon. Although new moons may be calculated quite precisely, the actual visibility of the crescent is difficult to predict. It depends on factors such as weather, the optical properties of the atmosphere, and the location of the observer. Therefore in some cases, it may be difficult to give accurate information in advance about when a new month will start. Furthermore, in some areas, Muslims depend on a local sighting of the moon, whereas in other areas a universal sighting is accepted. (i.e. if a new crescent is seen anywhere in the world it is accepted for communities the world over). Both are valid Islamic practices, but they may lead to different starting days for the months. Years are counted since the Hijra, that is, Prophet Mohammed’s (Peace be upon him) migration to Medina, which is assumed to have taken place, 16 July C.E. 622 (Julian calendar). On that date AH 1 started (AH = Anno Hegirae = year of the Hijra).