The wheel and axle are one of six simple machines, all of which are designed to make life easier for humans. Wheels can be found everywhere in the 21st century and are used a lot in transportation. Things like cars, bicycles, trucks, trains, and even planes all use wheels to move around.
The wheel is believed to have first been invented thousands of years ago by different ancient civilizations. Each civilization used the wheel in its own way. For example, the ancient Mesopotamians and civilizations in Asia used the wheel for work, to move building material and food. The Incas and Mayans used the wheel to entertain children but did not use the wheel for work or labor.

The wheel itself was an incredible invention because it greatly reduces friction, a force that makes it harder to move things. By mounting the wheel on an axle, humans could utilize carts and wheelbarrows, making it even easier to transport heavy objects. A wheel and axle system can also work as something known as a force multiplier. A force multiplier makes it easier to do work. For example, using just a little bit of strength can make a cart or wagon roll for a long time.