That is a HUGE question! @Zee @Gary_H_aka_Gary12
I will give due diligence to 1911’s for starters.
Thumb Safety: Physically blocks movement of the sear when the gun is cocked and the safety is ON.
Grip Safety: Physically prevents movement of the trigger when not engaged.
Disconnector: Disconnects the sear and trigger when the slide travels over it and pushes it down. It likewise frees the sear and trigger when released UP into the notch on the slide.
Half Cock Notch: Not really a safety it is an intermediate “catch” for a slow falling hammer as with a sear bounce event from dropping.
Series 80: The half cock notch remains but is irrelevant due to the firing pin lock assembly. An additional lever next to the sear that when the trigger is pulled the lever pushes up on a plunger in the slide allowing free movement of the firing pin. Otherwise the firing pin is heald in place by the plunger preventing a “inertia discharge” of a free floating firing pin.
In General Designs
Slide mounted safety’s: MOST, not all are two piece firing pins with the short part located in the safety barrel (housing if you prefer) when you rotate the safety it also rotates the firing pin out of alignment. Some pistols also de-cock the gun at the same time. Scary as he!! until you figure it out.
Frame mounted safety’s in general BLOCK something from moving, either the trigger or the sear USUALLY.
Revolvers: IN GENERAL most modern ones have some form of “transfer bar safety” a little flat bar that moves up the block the hammer from striking the floating firing pin as the hammer is not going at full speed. Modern (even old modern) revolvers have FLAT hammers that contact a floating firing pin, you can load all 6, 7, 8, 10 cylinders as you wish, some may not have a transfer bar safety.
If you have a revolver (or shot gun) with a “spike” on the hammer NEVER load the chamber it sits on and don’t dry fire them. This is how the old wives tail of not dry firing a shot gun (or any gun) came to be. The hammer with the spike actually entered a hole in the frame to contact the primer (it IS the firing pin) with metal being what it was in 1900 if there was nothing there to “catch” the blow the “spike” could shear off due to inertia = broke gun. Old DBL BBL (stage coach) shot guns were similar in that the firing pin was separate but again with nothing to HIT against it could shear off the point of the pin.
Multiple generations of people were trained NEVER to dry fire their weapons and it lingers on today. As a bit of range etiquette always ASK prior to dry firing someone else’s firearm. It’s prudent and professional.
I will defer to others for striker fired pistols as I have not cracked enough open to be fully versed in their operation. De-cockers have to each be examined on their own merit as I understand there are several ways to do it.
In general if the safety reaches into the guts of the rifle it is blocking the trigger AR-15, Rem 700 et al. If the safety is on the bolt it is a firing pin block. IMHO Paul Mauser had it right.
Edited because I kaint speel