A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single, specific day within such a system. A calendar is also a physical record of such a system. A calendar can also mean a list of planned events, such as a court calendar or a partly or fully chronological list of documents, such as a calendar of wills.
The Hijri calendar, also known as the Lunar Hijri calendar and as the Islamic, Muslim or Arabic calendar, is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the proper days of Islamic holidays and rituals, such as the annual period of fasting and the proper time for the Hajj. In almost all countries where the predominant religion is Islam, the civil calendar is the Gregorian calendar, with Syriac month-names used in the Levant and Mesopotamia but the religious calendar is the Hijri one.
Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months.
The Babylonian calendar was a lunisolar calendar with years consisting of 12 lunar months, each beginning when a new crescent moon was first sighted low on the western horizon at sunset, plus an intercalary month inserted as needed by decree. The calendar is based on a Sumerian predecessor preserved in the Umma calendar of Shulgi.
The intercalary month or epagomenal days of the ancient Egyptian, Coptic, and Ethiopian calendars are a period of five days in common years and six days in leap years in addition to those calendars' 12 standard months, sometimes reckoned as their thirteenth month. They originated as a periodic measure to ensure that the heliacal rising of Sirius would occur in the 12th month of the Egyptian lunar calendar but became a regular feature of the civil calendar and its descendants. Coptic and Ethiopian leap days occur in the year preceding Julian and Gregorian leap years.
The Islamic New Year, also called the Hijri New Year or Arabic New Year, is the day that marks the beginning of a new lunar Hijri year, and is the day on which the year count is incremented. The first day of the Islamic year is observed by most Muslims on the first day of the month of Muharram. The epoch of the Islamic era was set as the year of the emigration of Muhammad and his followers from Mecca to Medina, known as the Hijrah, which equates to 622 CE in the Gregorian calendar. All religious duties, such as prayer, fasting in the month of Ramadan, and pilgrimage, and the dates of significant events, such as celebration of holy nights and festivals, are calculated according to the Islamic calendar.
The Hijri year or era is the era used in the Islamic lunar calendar. It begins its count from the Islamic New Year in which Muhammad and his followers migrated from Mecca to Yathrib. This event, known as the Hijrah, is commemorated in Islam for its role in the founding of the first Muslim community (ummah).
Eid prayers, also referred to as Salat al-Eid, are holy holiday prayers in the Islamic tradition. The literal translation of the word "Eid" in Arabic is "festival" or "feast" and is a time when Muslims congregate with family and the larger Muslim community to celebrate.
The Javanese calendar is the calendar of the Javanese people. It is used concurrently with two other calendars, the Gregorian calendar and the Islamic calendar. The Gregorian calendar is the official calendar of the Republic of Indonesia and civil society, while the Islamic calendar is used by Muslims and the Indonesian government for religious worship and deciding relevant Islamic holidays.
The Berber calendar is the agricultural calendar traditionally used by Berbers. It is also known as the fellaḥi. The calendar is utilized to regulate the seasonal agricultural works.
The Arabic names of the months of the Gregorian calendar are usually phonetic Arabic pronunciations of the corresponding month names used in European languages. An exception is the Syriac calendar used in Iraq and the Levant, whose month names are inherited via Classical Arabic from the Babylonian and Hebrew lunisolar calendars and correspond to roughly the same time of year.
The Rumi calendar, a specific calendar based on the Julian calendar, was officially used by the Ottoman Empire after Tanzimat (1839) and by its successor, the Republic of Turkey until 1926. It was adopted for civic matters and is a solar based calendar, assigning a date to each solar day.
The Bengali Calendar or Bangla Calendar, colloquially, is a solar calendar used in the Bengal region of the Indian subcontinent. A revised version of the calendar is the national and official calendar in Bangladesh and an earlier version of the calendar is followed in the Indian states of West Bengal, Tripura and Assam. The New Year in the Bengali calendar is known as Pohela Boishakh.
Fasli Calendar or Fasli era, Fasli is an Arabic word imported to the Urdu language.
The Solar Hijri calendar is a solar calendar and one of the various ancient Iranian calendars. It begins on the March equinox as determined by astronomical calculation for the Iran Standard Time meridian and has years of 365 or 366 days. It is the modern principal calendar of both Iran and Afghanistan, and is sometimes also called the Shamsi Hijri calendar, and abbreviated as SH and, sometimes, HS.
The month names in Turkish are derived from three languages: either from Latin, Levantine Arabic, or from a genuine Turkish word. The Arabic-Aramaic month names themselves originate in the ancient Babylonian calendar, and are therefore cognate with the names of months in the Hebrew calendar, specifically Shevat, Nisan, Tammuz and Elul. The original Babylonian months were actual lunar months, as the Hebrew months of the same names are to this day, much like months in the Islamic calendar. Turkey has used Gregorian AD year numbering officially since 1926, though Gregorian calendar dates were in use since March 1917. The names of the months from February to September had been used in the now abandoned Rumi calendar, with the other four still retaining their old Arabic/Aramaic names. In 1945, three of them received names of Turkish origin.
In Bahrain, both the Gregorian and Islamic calendars are used in government transactions. Short dates are written in "Day/month/year" from; when writing in Arabic and English:
Several calendars have been used in pre-Islamic Arabia. Inscriptions of the ancient South Arabian calendars reveal the use of a number of local calendars. At least some of these South Arabian calendars followed the lunisolar system. For Central Arabia, especially Mecca, there is a lack of epigraphic evidence, but details are found in the writings of Muslim authors of the Abbasid era. Some historians maintain that the pre-Islamic calendar used in Central Arabia was a purely lunar calendar similar to the modern Islamic calendar. Others concur that the pre-Islamic calendar was originally a lunar calendar, but suggest that about 200 years before the Hijra it was transformed into a lunisolar calendar, which had an intercalary month added from time to time to keep the pilgrimage within the season of the year when merchandise was most abundant.
The adoption of the Gregorian Calendar was an event in the modern history of most cultures and societies, marking a change from their traditional dating system to the modern dating system, the Gregorian calendar, that is widely used around the world today. Some states adopted the new calendar from 1582, some did not do so before the early twentieth century, and others did so at various dates between; however a number continue to use a different civil calendar. For many the new style calendar is only used for civil purposes and the old style calendar remains used in religious contexts. Today, the Gregorian calendar is the world's most widely used civil calendar. During – and for some time after – the change between systems, it has been common to use the terms Old Style and New Style when giving dates, to indicate which calendar was used to reckon them.