The Katyusha rocket launcher is a type of weapon that was used a lot during World War II. It looks like a truck with lots of long tubes sticking out the back. People load rockets into these tubes and a soldier or person sitting in the truck can use a special switch to launch them. The rockets then fly through the air and explode near or on their targets. The Katyusha rocket launcher is a very powerful weapon and can even launch several rockets at once, making them very dangerous and devastating.