What are the main sources of wealth for the Catholic Church?

To many monasteries of the Catholic Church, kings and governments of countries donated rather large land plots, on which either ordinary monks or peasants worked. There were no taxes levied on these lands. Rich offerings also filled the treasury of the church. Taking advantage of their position, some representatives sold the so-called indulgences (absolution). Each church action had to be paid for. Sometimes the “guilty” monarch or nobleman made amends for his guilt with money, land, jewelry, perhaps even seized church utensils.