San Fermín celebrates Saint Fermín, the co-patron saint along with Saint Francis Xavier of Navarra (the region in which Pamplona is located). Each town in Spain has one or two patron saints and celebrates the day of the patron saint according to the Catholic calendar. The patron saint day of Saint Fermín was once celebrated on October 10. However, later in history, this celebration was combined with celebrations of the beginning of summer and moved to July, when the weather in Pamplona is much better. The origins of the festival date back to the 14th Century. Since then, the festival has evolved to include different events, including bullfighting.
Spain is a majority Catholic country, and religion is very important to its culture and traditions, including festivals. The San Fermín festival has its roots in the local religion, but has since become an international festival that includes a lot of other activities, too!