The Middle Ages was a time in history a long time ago, kind of like how your grandparents were young a long time ago. It lasted from about the 5th century to the 15th century in Europe. During this time, many important things happened and people did things differently than they do now.
One of the big things that happened during the Middle Ages was that people started living in castles. Castles are big, strong buildings that people could go to if they were being attacked. They were built with big walls, towers, and sometimes even a moat around them. Inside the castle, people would have everything they needed to survive; like food, water, weapons, and even a church. The person who lived in the biggest castle was called a King, and they were in charge of everything.
Another important thing that happened during the Middle Ages was that people started going on these big trips called a crusade. A crusade is when people would travel to another country in order to fight. They would do this because they believed it was important to protect their religion. A religion is like a really important set of beliefs that people have in their heart, and for some people, it's really important to defend it.
During the Middle Ages, people also believed that it was really important to have a good life after they died. They believed that what they did in this life would determine where they would end up in the next life. In order to make sure they had a good life after they died, people did things like build big, beautiful churches and give money to the church. They also prayed a lot and did things that they believed God would like, like help the poor and sick.
Overall, the Middle Ages was a really different time than what we have now. People did things differently, but it was an important time in history that helped to shape the way we live now.