San Patricio, or Saint Patrick, is the patron saint of Ireland. He is celebrated for bringing Christianity to the Irish people in the 5th century. According to tradition, he used the shamrock to explain the concept of the Holy Trinity, which represents the Father, the Son, and the Holy Spirit. His feast day, known as Saint Patrick's Day, is observed on March 17th. This day commemorates his death and is marked by various celebrations, including parades and wearing green attire. San Patricio is also associated with the legend of driving snakes out of Ireland, symbolizing the eradication of paganism.