The reformation started when Martin Luther wrote his 95 theses on the church door at Wittenberg, in 1517, he didn't know it would start a whole new movement. It started in Germany, and spread across Europe and included almost every important nation in Europe.
The printing press helped during the reformation by printing and circulating copies of the Bible in different languages, also books and pamphlets written by the reformers.
The five solae are Latin phrases used by the reformers, that sums up the beliefs of the Protestant reformers and differences of the Catholic church.
The Catholic church, however, was not very pleased with the new movement. To try to stop this movement, the Catholic church called the Council of Trent and organized a counter-reformation movement.
The counter-reformation included 4 parts:
The Council of Trent rejected any agreement from the Protestants or the ideas of the Reformers.
Regardless of the Council of Trent upholding the Catholic Church's practices, the Reformation still spread. Soon, several countries in Europe officially became Protestants nations, these countries included Germany, Switzerland, Netherlands, and England. The Reformation couldn't be stopped and it changed Europe's future as it progressed.