Christian monasticism is when people follow a set of rules that help them live a life according to Jesus' teachings. Monks and nuns are people who choose to devote their lives to living in this way. Monks and nuns live in groups called monasteries or convents, and they work and pray together to help each other grow spiritually. They often wear special clothing, like long robes and hoods, that are usually plain and simple. It's their way of showing that they are not looking to live a showy lifestyle. Instead, they focus on being humble and unselfish and loving God and other people.