The Higgs boson is like an invisble piece of something called the Higgs field that makes up the universe. This field is kind of like an invisible blanet that is everywhere and all around us. Inside the field are tiny particles called Higgs bosons. They are the smallest pieces of the field and act like glue that holds things together. When other bits of matter come close to the Higgs boson particles, they can stick and stay together so they become "heavy". Without Higgs bosons, these particles wouldn't be able to stick together and you wouldn't get things like atoms and molecules that make up everything in our universe.