Roll-on/roll-off

Okay kiddo, sometimes big things need to be moved from one place to another, like boats or cars, but it's not easy to just drive them down the road. So, people came up with a clever way to move them by putting them on a special kind of ship.

This kind of ship has a big door on the back that opens up so the vehicles can be driven onto the ship. Then, the ship closes the door and it looks like a big metal box with wheels sticking out.

When the ship gets to the other side, it opens the door again and the vehicles can drive down off the ship. This is called "roll-on/roll-off" because the vehicles can roll on and roll off the ship like they're on a big ramp.

It's a really convenient way to transport lots of vehicles at once without having to drive them all the way there. Cool, huh?