What is the part that contains the mechanism to fire the bullet?

The part that contains the mechanism to fire the bullet is the trigger. The trigger is a crucial component of a firearm that activates the firing mechanism when it is pulled. When the trigger is pulled, it releases the firing pin or striker, which then strikes the primer of the cartridge, igniting the gunpowder and discharging the bullet.

Understanding the function of the trigger is essential for safe handling and operation of a firearm. It is designed specifically to ensure that the shooter can easily and effectively control when the firearm discharges, representing a key aspect of firearm mechanics and safety.