Revolvers
A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing.
The first revolver (flintlock revolver) ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson. The first cartridge revolvers finally were Smith and Wessons and were produced around 1856.
Semi-Automatics
A semi-automatic pistol is a type of handgun which uses a single chamber and barrel, with a mechanism powered by the previous shot to load a fresh cartridge into the chamber. One round is fired each time the trigger of a semi-automatic pistol is pulled.
A semi-automatic pistol harnesses the energy of one shot to reload the chamber for the next, typically via recoil operation, blowback, or gas operation. After a round is fired, the spent casing is ejected and a new round from the magazine is loaded into the chamber, allowing another shot to be fired as soon as the trigger is again pulled.