The Hijri era (Arabic: التقويم الهجري, romanized: at-taqwīm al-hijrī) is the calendar era used to record dates in the Islamic world. Its epoch (start point of the era) is the year in which Muhammad and his followers migrated from Mecca to Yathrib (now Medina), in 622 CE. This event, known as the Hijrah, is commemorated in Islam for its role in the founding of the first Muslim community (ummah). Time in this era is measured by two principal calendars: the lunar Hijri calendar (known in the West as the "Islamic calendar") which counts lunar years since the Hijrah and which is used by most Muslims around the world; and the solar Hijri calendar (also known as the "Persian calendar") which counts solar years since the Hijrah and which is used in Iran.
In the West, dates in the lunar Hijri calendar are denoted as AH (Latin: Anno Hegirae) or Hijri year (Arabic: سنة هجرية, romanized: sanat hijriyya, lit. 'in the year of the Hijra') in the style of the Christian/Common (AD/CE) and Jewish eras (AM) and can similarly be placed before (preferably) or after the date. In predominantly Muslim countries, it is also commonly abbreviated H ("Hijra") from its Arabic abbreviation hāʾ (هـ). Years prior to AH 1 are reckoned in English as BH ("Before the Hijra"), which follows the date. Dates in the solar Hijri calendar are denoted as SH. The current year according to the lunar Hijri calendar is AH 1447; according to the solar Hijri calendar the current year is SH 1404. The difference in numbering arises because a lunar year is about eleven days shorter than a solar year.
