Wearing green is one of the most important aspects of Irish culture and celebrating St. Patrick’s Day, but not everyone knows why people wear green when celebrating the holiday worldwide. According to TIME Magazine,

While St. Paddy’s is typically known as a big drinking holiday, those who are abstaining for whatever reason need not be left out. Nonalcoholic beer has been growing in popularity over the last few years, and the Irish king of beers has taken a swing at it, too.

St. Patrick’s Day usually conjures images of partying, Catholicism, Irish nationalism and, perhaps most famously, the color green: green clothes, green shamrocks, green beer and green rivers. But the holiday used to be a solemn feast day when you’d be far more likely to see the color blue.