What punishment did popes use to control kings?

Popes historically wielded significant influence over kings through the use of excommunication and interdict. Excommunication barred individuals from participating in the sacraments and community of the Church, while interdict suspended religious services in a king's realm, effectively alienating the population from their faith. These measures pressured rulers to comply with papal authority, as they risked losing legitimacy and support from their subjects. Additionally, the threat of these punishments could be a powerful tool in negotiating political power and influence.