Every year on December 20 or 21, Iranians celebrate the arrival of winter, the renewal of the sun and the victory of light over the darkness at Yalda Night.
The longest and darkest night of the year is a time when friends and family gather (most often at the home of the oldest member) to eat, drink and read poetry (especially Hafez) until well after midnight.
Watermelon, pomegranate and dried nuts are served as a tradition and classical poetry and ancient mythologies are read at the meeting.
The red color in these fruits symbolizes the red tones of dawn and brightness of life. The Divan-e-Hafez poems, which can be found on the shelves of most Iranian families, are mixed with people's lives and are read or recited on several occasions like this festival and in Nowruz.
Yalda has its root in the belief of Zoroaster, to be exact, Mithraism religion. The Mithraists assumed that Mithra, the Persian god of light and truth, was born of a virgin mother in the morning of the longest night of the year, symbolizing the sun god overcoming the powers of darkness.
Central Asian countries such as Afghanistan, Tajikistan, Uzbekistan, Turkmenistan and some Caucasian states like Azerbaijan and Armenia share the same tradition well and celebrate Yalda Night annually at this time of year.
Yalda night was officially added to Iran's national heritage list during a special ceremony in 2008.