What distinguishes a revolver from a semi-automatic pistol?

A revolver is distinguished from a semi-automatic pistol primarily by its design feature of a rotating cylinder, which holds multiple rounds of ammunition. This cylinder rotates in alignment with the barrel as the trigger is pulled, allowing each round to be fired sequentially. Each time the trigger is pulled, the cylinder rotates to the next chamber, making it necessary for the revolver to be manually cocked or may have a double-action mechanism that cocks the hammer automatically.

In contrast, a semi-automatic pistol uses a magazine to store ammunition and relies on the energy from the fired round to eject the spent casing, load the next round, and reset the firing mechanism in a single continuous action. The design and operational mechanisms of each type of firearm serve to fulfill different requirements in terms of firing speed, capacity, and user handling. Thus, the presence of a rotating cylinder is a defining characteristic that sets revolvers apart from semi-automatic pistols.