One of the lessons that I cover in my Beginner class is about Single Action and Double Action. I get a lot of questions about what the differences are.
With single-action handguns (SA), pulling the trigger performs only one function.
The hammer or the striker moves and fires the gun when the shooter pulls the trigger.
So how does the handgun get cocked? In a single-action semi-automatic handgun, the firearm is cocked when the slide is racked, and the recoil and slide movement automatically cock the firearm for each subsequent shot.