Pope Innocent IV was the 180th pope of the Roman Catholic Church, serving from 1243 to 1254. He is best known for his efforts to strengthen papal authority and his involvement in the political conflicts of his time, particularly with the Holy Roman Empire. Innocent IV was also notable for his role in the Fourth Lateran Council, which addressed various church reforms. During his papacy, Innocent IV faced challenges from powerful rulers, including Frederick II, the Holy Roman Emperor. He was the first pope to formally use the term "excommunication" against a reigning emperor, which highlighted the growing tensions between the church and secular powers. His reign marked a significant period in the history of the papacy.