Imagine a tank! It has a big, long tube sticking out, right? That's the gun barrel! Think of it like a super-strong, super-big pipe or a tunnel for the tank's big bullet, which we call a shell.
Outside, it looks like a long, thick metal tube. It's made of very, very strong metal so it doesn't break when the tank shoots. The metal is super tough, like the strongest steel you can imagine!
Inside, it's hollow, like a tunnel! This is the path where the tank's big shell travels really, really fast when it's shot out. Just like a tunnel for cars, but for tank shells!
The end, called the muzzle, is the very front part where the shell comes out. Sometimes it has a special shape or bumps on it. This helps control the big push, like a kick, when the gun fires, so the tank doesn't jump back too much.
So, it's basically a strong, hollow metal tube that gives the shell a super-fast push to fly far away! It has strong metal outside, a hollow tunnel inside, a special muzzle end, and shoots shells very far!