Nicolaus Otto was a man who lived a long time ago and helped make cars work better. When cars were first invented, they didn't work very well and they were loud and smelly. But Nicolaus Otto helped fix that by inventing something called the four-stroke engine.
This four-stroke engine works kind of like a bike. On a bike, you pedal and the wheels move. In the four-stroke engine, gas and air are mixed together and then it explodes like a balloon popping. This explosion makes the engine move and the car go forward.
Nicolaus Otto was really smart and worked hard to make the four-stroke engine better and better. People started using cars more and more and it made their lives easier. Now we can go places really fast and not have to walk or ride a horse.
So, Nicolaus Otto was an important person who helped make cars better and easier to use.