Mark 1 is a nickname for a very important book in the Bible. It's a book all about a man named Jesus who lived a long, long time ago in a place called Israel.
In Mark 1, we learn about some of the amazing things that Jesus did while he was on Earth. He healed sick people and even made blind people be able to see again. He also talked to lots of people about how they should be kind and loving to each other, just like how he was kind and loving to them.
The book is important because it helps us understand more about Jesus and what he was like. People still read it today to learn about him and to try to be like him.