Your turbocharger. It's the snail of mystery attached to your engine, allowing it to breathe in more deeply. With the wonders of forced induction, a smaller engine can create the horsepower and torque of a larger-displacement engine.
There are many parts to a turbocharger, which means you might have questions about any number of those parts. Today on Engineering Explained you'll be able to cross one of those parts off your list: the wastegate.
With a turbo, it's hot exhaust gases that make your world go 'round. At a certain point, however, your boost pressure is sufficient and some of that hot air can bypass the exhaust turbine. This is the point at which your wastegate actuator starts to respond.
The wastegate opens up and the exhaust gases have a different path to freedom. You've opened up a bypass valve that sends this hot air in a different direction.
Engineering Explained goes into a bit more detail (with a lot more clarity) than that. Also, the video above briefly explains the difference between internal and external wastegates. Now that you possess this knowledge, go forth into the world and impress your automotive enthusiast friends the next time the topic of turbos spools up.