February is the second month of the year in the Julian and Gregorian calendars. The month has 28 days in common years and 29 in leap years, with the 29th day being called the leap day. February is the third and last month of meteorological winter in the Northern Hemisphere. In the Southern Hemisphere, February is the third and last month of meteorological summer.
The French Republican calendar, also commonly called the French Revolutionary calendar, was a calendar created and implemented during the French Revolution, and used by the French government for about 12 years from late 1793 to 1805, and for 18 days by the Paris Commune in 1871, and meant to replace the Gregorian calendar.
The Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year. The Julian calendar is still used as a religious calendar in parts of the Eastern Orthodox Church and in parts of Oriental Orthodoxy as well as by the Amazigh people.
A leap year is a calendar year that contains an additional day compared to a common year. The 366th day is added to keep the calendar year synchronised with the astronomical year or seasonal year. Since astronomical events and seasons do not repeat in a whole number of days, calendars having a constant number of days each year will unavoidably drift over time with respect to the event that the year is supposed to track, such as seasons. By inserting ("intercalating") an additional day—a leap day—or month—a leap month—into some years, the drift between a civilization's dating system and the physical properties of the Solar System can be corrected.
A month is a unit of time, used with calendars, that is approximately as long as a natural phase cycle of the Moon; the words month and Moon are cognates. The traditional concept of months arose with the cycle of Moon phases; such lunar months ("lunations") are synodic months and last approximately 29.53 days, making for roughly 12.37 such months in one Earth year. From excavated tally sticks, researchers have deduced that people counted days in relation to the Moon's phases as early as the Paleolithic age. Synodic months, based on the Moon's orbital period with respect to the Earth–Sun line, are still the basis of many calendars today and are used to divide the year.
The Roman calendar was the calendar used by the Roman Kingdom and Roman Republic. Although the term is primarily used for Rome's pre-Julian calendars, it is often used inclusively of the Julian calendar established by Julius Caesar in 46 BC.
The Coptic calendar, also called the Alexandrian calendar, is a liturgical calendar used by the farming populace in Egypt and used by the Coptic Orthodox and Coptic Catholic churches. It was used for fiscal purposes in Egypt until the adoption of the Gregorian calendar on 11 September 1875. This calendar is based on the ancient Egyptian calendar. To avoid the calendar creep of the latter, a reform of the ancient Egyptian calendar was introduced at the time of Ptolemy III which consisted of adding an extra day every fourth year. However, this reform was opposed by the Egyptian priests, and the reform was not adopted until 25 BC, when the Roman Emperor Augustus imposed the Decree upon Egypt as its official calendar. To distinguish it from the Ancient Egyptian calendar, which remained in use by some astronomers until medieval times, this reformed calendar is known as the Coptic or Alexandrian calendar. Its years and months coincide with those of the Ethiopian calendar but have different numbers and names.
In the Gregorian calendar, New Year's Day is the first day of the calendar year, 1 January. Most solar calendars, such as the Gregorian and Julian calendars, begin the year regularly at or near the northern winter solstice. In contrast, cultures and religions that observe a lunisolar or lunar calendar celebrate their Lunar New Year at varying points relative to the solar year.
The Swedish calendar or Swedish style was a calendar in use in Sweden and its possessions from 1 March 1700 until 30 February 1712. It was one day ahead of the Julian calendar and ten days behind the Gregorian calendar. Easter was calculated astronomically, with a minor exception, from 1740 to 1844.
The epact used to be described by medieval computists as the age of a phase of the Moon in days on 22 March; in the newer Gregorian calendar, however, the epact is reckoned as the age of the ecclesiastical moon on 1 January. Its principal use is in determining the date of Easter by computistical methods. It varies from year to year, because of the difference between the solar year of 365–366 days and the lunar year of 354–355 days.
Dominical letters or Sunday letters are a method used to determine the day of the week for particular dates. When using this method, each year is assigned a letter depending on which day of the week the year starts with. The Dominical letter for the current year 2025 is E.
Calendar reform or calendrical reform is any significant revision of a calendar system. The term sometimes is used instead for a proposal to switch to a different calendar design.
A leap year starting on Thursday is any year with 366 days that begins on Thursday 1 January, and ends on Friday 31 December. Its dominical letters hence are DC. The most recent year of such kind was 2004 and the next one will be 2032 in the Gregorian calendar or, likewise, 2016 and 2044 in the obsolete Julian calendar.
In Christianity, a name day is a tradition in many countries of Europe and the Americas, as well as Christian communities elsewhere. It consists of celebrating a day of the year that is associated with one's baptismal name, which is normatively that of a biblical character or other saint. Where they are popular, individuals celebrate both their name day and their birthday in a given year.
This is the current Swedish name day calendar, adopted in 2001 by a work group led by the Swedish Academy. The new list has no official status, but is nevertheless used by most publishers. Several name day lists existed after 1972, when the old name day calendar lost its official status. The new list will be updated every 15 years. Some of the names below are linked to the original saints or martyrs from which they originate.
A birthday is the anniversary of the birth of a person, or figuratively of an institution. The birthdays of people are celebrated in numerous cultures, often with birthday gifts, birthday cards, a birthday party, or a rite of passage.
The Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull Inter gravissimas issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years differently so as to make the average calendar year 365.2425 days long, more closely approximating the 365.2422-day "tropical" or "solar" year that is determined by the Earth's revolution around the Sun.
The Solar Hijri calendar is the official calendar of Iran. It is a solar calendar and is the one Iranian calendar that is the most similar to the Gregorian calendar, being based on the Earth's orbit around the Sun. It begins on the March equinox as determined by the astronomical calculation for the Iran Standard Time meridian and has years of 365 or 366 days. It is sometimes also called the Shamsi calendar, Khorshidi calendar, or Persian calendar. It is abbreviated as SH, HS, AP, or, sometimes as AHSh, while the lunar Hijri calendar is usually abbreviated as AH.
