Nowruz is the Iranian, or Persian, New Year and it begins this year on March 21.
It is celebrated in areas that were once part of the Persian Empire and in places where people from those areas have later settled.
The festival is at least 3,000 years old, and is celebrated from Albania to parts of northwestern China, although it is most widely observed in Iran and Central Asia.
Like most New Year festivals, it is a time for families to gather, exchange gifts and visit one another.
It is preceded by CharshanbeSuri, which takes place in the week before Nowruz. The evening event features fires, which people jump over, and fireworks.
Celebrants prepare for Nowruz by cleaning houses and buying new clothes. Many wear new clothes on Nowruz, and Parsis (or Zoroastorians) wear gold and silver costumes.
One feature of the celebrations in Iran is the Haft Seen, a decorated table, where family members wait around for the exact beginning of Nowruz - the spring equinox, when the sun is directly over the equator and the north and south hemispheres receive equal amounts of light.
Nowruz, which literally means new day, will then continue for 11 days.
In Afghanistan, the festivities include buzkashi tournaments. Buzkashi is a Central Asian sport in which horse riders try to deposit a goat's carcass in a goal.
In China, Nowruz is celebrated in the Xinjiang Uygur autonomous region by Uygur, Tajik, Salar and Kazakh ethnic groups.