Feasting on fresh fruits from the summer season and reciting works by 14th century Persian poet Hafez, Iranians all around the world stay up to mark the start of winter.
"It's not an official holiday in Iran, but similar to many other ancient traditions, it has become a significant cultural celebration observed by all Iranians," said Bita Milanian, executive director of Farhang Foundation, a nonprofit that celebrates Iranian art and culture in Southern California.
The celebration, which translates to "Night of Birth," has come to symbolize many things for Iranians, said Touraj Daryaee, a
"This is part of Iranian tradition where evil will run havoc on the longest night of the year," he said. "So people gather to be together until evil is gone… it's an old idea where you need protection from evil."
When the sun rises, light shines and goodness prevails, he said.
During Yalda, people traditionally make wishes and turn to poetry for answers.
"Each member of the family makes a wish and randomly opens Hafez's book of poems and recites the poem, which is believed to be an interpretation to the wish," Milanian said.
Fruits, such as pomegranates, are served in thanks for the blessings of the season and as prayers for prosperity in the next year, she added.
In Southern California, numerous parties are organized to celebrate Yalda, including a sold-out event hosted by the Farhang Foundation on Friday night that featured popular Persian poets and musicians.
At an event hosted by the Iranian Student Group, about 100 students gathered to celebrate by eating fruit, drinking tea, listening to live Persian music and playing backgammon.
"We are having a good time and really just enjoying our heritage," said the group's president, Roxy Tabrizi, a UCLA junior. "It's not about religion or age — it's about community."
Former club president Najva Akbari agreed: "We are a big family here. Family is an important part of the Persian culture and this night is another way to celebrate that."