May 26 is World Redhead Day, an unofficial holiday that gives red-haired people a public moment in the sun and, in many places, a reason to gather. Around the world, from the Netherlands to Ireland, the United Kingdom and the United States, people mark the day with themed meetups, festivals and photo shoots.

The holiday emerged as a response to something less celebratory: the stereotypes, jokes and bullying many redheads have faced because of how they look. Redheads make up just 1% to 2% of the world’s population, which helps explain why the day has become a marker of identity as much as a party. On social media, users post old photos and send greetings to red-haired friends, turning a niche observance into a small annual wave of recognition.

There are two versions of how the day began. One says activists in the Netherlands launched it in the mid-2000s to support red-haired people. Another links it to Dutch artist Bart Rovenhorst, whose casting call for a red-haired model was expected to draw only a few people but instead brought in more than 150 redheads. That turnout eventually grew into the Redhead Days festival, which now brings together thousands of people from different countries every year.

The day’s reach also reflects a larger story about red hair itself. Scientists say the color comes from a mutation in the MC1R gene, and the highest concentration of redheads lives in Ireland and Scotland. Research has also found that redheads can react differently to pain, the sun and certain medications. Long before those findings, people viewed red hair with suspicion; in the Middle Ages, redheads were sometimes considered strange or associated with the supernatural.

That history is part of why the holiday has lasted. It is unofficial, but it is widely recognized in multiple countries and has taken on a meaning that goes beyond hair color. For many who celebrate World Redhead Day, it is a small annual reminder that something once used to single people out can also become a reason to stand together.