Sizdah-bedar is the final day of the two-week celebrations of the Persian New Year, which marks the beginning of spring in the northern hemisphere.
It is an occasion for outdoor activities, picnics, and spending time with friends and family in the nature.
The tradition has been celebrated for some three thousand years in Iran, Tajikistan and Afghanistan and among other Persian-speaking communities.
Sizdah-bedar means getting rid of number 13. In Persian mythology, 13 is the bad luck number.
Now Sizdah-bedar is believed to chase away the bad luck and bring good vibes.
The event is also called the Festival of Nature, and it is an occasion to raise awareness about the need to preserve the environment.