Design of the firearm
Two basic styles of firearm actions are single action and double action.
Half barrel is not a type of firearm action.
Type of firearm action
The action spring is typically housed within the stock or buffer tube of a firearm. It provides the necessary tension to cycle the firearm's action and chamber a new round.
No such thing. The Glock is not a double action firearm.
Action or reciever
Stock , Barrel & Action
Not sure if this is what you're asking, but strictly speaking, the action of a firearm refers to how the trigger system works. Some firearms are single action, some are double action, some are double action only, some are variants. Glocks are called "Safe Action" which is Glocks propietary term for how their trigger works.
you will find it on the barrel or action of the firearm
The simplest would be a single shot muzzle loading firearm. In modern cartridge firearms, a break action firearm. They are made as rifles, shotguns and pistols.
There are more than two basic types. There are revolvers, semi autos, breach action, bolt action, etc.