Protestantism is a type of religion that is different from other types like Catholicism or Judaism. It started a long time ago when a man named Martin Luther asked questions about the way the Catholic Church was doing things. He thought some things were wrong and didn't make sense. So he started talking to other people about his ideas.
Lots of people started listening to what Martin Luther had to say and they agreed with him. They thought the Catholic Church needed to change. These people became known as Protestants because they were "protesting" against the Catholic Church.
Protestants believe that people should read and interpret the Bible for themselves, instead of just listening to what a priest says about it. They also believe that you don't need to go to a priest to confess your sins, that you can talk directly to God. And they believe in different ways of worshiping than what the Catholic Church does.
Today, there are many different types of Protestant churches, like Baptists, Methodists, Lutherans, and many more. Each one has its own way of doing things, but they all share the basic beliefs that started with Martin Luther and the other Protestants long ago.