Nowrūz (Persian: نوروز, IPA: [nouˈɾuːz], meaning "[The] New Day") is the name of the Iranian New Year in Iranian calendars and the corresponding traditional celebrations. Nowruz is also widely referred to as the "Persian New Year".
Nowruz is celebrated and observed by Iranian peoples and the related cultural continent and has spread in many other parts of the world, including parts of Central Asia, Caucasus, South Asia, Northwestern China, the Crimea and some groups in the Balkans.
Nowruz marks the first day of spring and the beginning of the year in Iranian calendar. It is celebrated on the day of the astronomical vernal equinox, which usually occurs on March 21 or the previous/following day depending on where it is observed. As well as being a Zoroastrian holiday and having significance amongst the Zoroastrian ancestors of modern Iranians, the same time is celebrated in parts of the South Asian sub-continent as the new year. The moment the Sun crosses the celestial equator and equalizes night and day is calculated exactly every year and Iranian families gather together to observe the rituals.
Originally being a Zoroastrian festival, and the holiest of them all, Nowruz is believed to have been invented by Zoroaster himself, although there is no clear date of origin. Since the Achaemenid era the official year has begun with the New Day when the Sun leaves the zodiac of Pisces and enters the zodiacal sign of Aries, signifying the Spring Equinox.
The Jewish festival of Purim is probably adopted from the Persian New Year. It is also a holy day for Sufis, Ismailis, Alawites, Alevis, and adherents of the Bahá'í Faith.
The term Nowruz in writing, first appeared in Persian records in the 2nd century AD, but it was also an important day during the time of the Achaemenids c. 548–330 BC), where kings from different nations under the Persian empire used to bring gifts to the Emperor, also called King of Kings (Shahanshah), of Persia on Nowruz. The significance of Nowruz in the Achaemenid empire was such that the great Persian king Cambyses II's appointment as the king of Babylon was legitimized only after his participation in the New Year festival (Nowruz).http://en.wikipedia.org/wiki/Nowruz