April (pronunciation) is the fourth month of the year in the Gregorian Calendar, and one of four months with a length of 30 days. April was originally the second month of the Roman calendar, before January and February were added by King Numa Pompilius about 700 BC. It became the fourth month of the calendar year (the year when twelve months are displayed in order) during the time of the decemvirs about 450 BC, when it also was given 29 days. The derivation of the name (Latin Aprilis) is uncertain. The traditional etymology is from the Latin aperire, "to open," in allusion to its being the season when trees and flowers begin to "open," is supported by comparison with the modern Greek use of ἁνοιξις (opening) for spring. Since most of the Roman months were named in honor of divinities, and as April was sacred to Venus, the Festum Veneris et Fortunae Virilis being held on the first day, it has been suggested that Aprilis was originally her month Aphrilis, from her Greek name Aphrodite (Aphros), or from the Etruscan name Apru. Jacob Grimm suggests the name of a hypothetical god or hero, Aper or Aprus.

The Anglo-Saxons called April Oster-monath or Eostur-monath, The Venerable Bede says that this month is the root of the word Easter. He further speculates that the month was named after a goddess Eostre whose feast was in that month. St George's day is the twenty-third of the month; and St Mark's Eve, with its superstition that the ghosts of those who are doomed to die within the year will be seen to pass into the church, falls on the twenty-fourth. In China the symbolic ploughing of the earth by the emperor and princes of the blood takes place in their third month, which frequently corresponds to our April. The Finnish called this month Huhtikuu, or 'Burnwood Month', when the wood for beat and burn clearing of farmland was felled.

The "days of April" (journées d'avril) is a name appropriated in French history to a series of insurrections at Lyons, Paris and elsewhere, against the government of Louis Philippe in 1834, which led to violent repressive measures, and to a famous trial known as the procès d'avril.

The birthstone of April is the diamond, and the birth flower is typically listed as either the Daisy or the Sweet Pea.

April starts on the same day of the week as July in all years, and January in leap years.

April holidays and events

• Sexual Violence Awareness Month
• National Poetry Month - in United States
• National Arab American Heritage Month - in United States
• Jazz Appreciation Month
• April Fools' Day - April 1
• April 1 is the first day of Japanese fiscal year. Major Japanese companies usually have Nyushashiki (entry ceremony for companies) for new employees those who newly hired after their graduation from schools, on this day.
• Japanese school calendar also starts from April 1, although Nyugakushiki (entry ceremony for schools) are usually held later, around second week of April.
• World Autism Awareness Day - April 2
• Arbor Day- in Korea - April 5
• End of Tax Year (UK) - April 5
• World Health Day- April 7
• Buddha's Birthday - Traditional Date - April 8
• Araw ng Kagitingan, also known as "Bataan Day" (Philippines) - April 9
• Thai New Year in Thailand - april 13
• Khmer New Year in Cambodia - April 13
• Tax Day - April 15 (in US)
• Boston Marathon - Third Monday
• Passover begins on the fifteenth day of Nisan, which in 2008 begins at sunset on April 19
• 4:20- April 20
• Patriots' Day- April 21
• Earth Day - April 22
• Conch Republic Independence Celebration (Key West, Florida) - April 23
• St George's Day Patron Saint Celebration (England, Europe) - April 23
• Birthday of Sgt. Jacob Caldwell, Journalist, U.S. Army - April 24
• ANZAC Day (Australia and New Zealand) - April 25
• Carnation Revolution (Portugal) - April 25
• Freedom Day (South Africa) - April 27
• April 29 is a Japanese national holiday, as Shōwa Day since 2007. It has been celebrated as The Emperor's Birthday from 1927 to 1988, then renamed as Greenery Day after Hirohito's death in 1989.
• Koninginnedag (Kingdom of the Netherlands) - April 30
• Arbor Day - last Friday of April in United States
• Take Our Daughters And Sons To Work Day, usually fourth Thursday (United States)
• London Marathon - usually fourth Sunday
• Easter - two days after Good Friday