Before the year 1059, the way Popes were chosen (like the boss of the Catholic Church) was different from how it is done now. Basically, back then, the people who had the most power and influence were the ones who got to choose the Pope. These people were usually important leaders of the Catholic Church or rulers of countries that were very close to the Church.
When the Pope died, the people who had the power would get together in a group called the conclave. This conclave was like a secret meeting where they would talk about who should be the next Pope. Sometimes, these meetings could last for months, and the people involved would argue a lot about who should be the next Pope.
After they finally agreed on who the new Pope should be, they would make an announcement to the people. The new Pope would then be crowned in a special ceremony called the papal coronation. This ceremony was very grand and involved lots of rituals and fancy clothes.
Sometimes, people were not happy with the person who was chosen as the new Pope. This could cause a lot of problems and even lead to wars! But eventually, the Catholic Church decided that they needed to change the way they chose Popes to make things more fair and less controversial. So, they created new rules in 1059, which are still used today.