Bolt action is a type of manual firearm action that is operated by directly manipulating the bolt via a bolt handle, which is most commonly placed on the right-hand side of the weapon (as most users are right-handed).
Most bolt-action firearms use a rotating bolt design, where the handle must first be rotated upward to unlock the bolt from the receiver, then pulled backward to open the breech and allowing any spent cartridge case to be extracted and ejected. This also cocks the striker within the bolt (either on opening or closing of the bolt depending on the gun design) and engages it against the sear. Upon the bolt being pushed back forward, a new cartridge (if available) is pushed out of the magazine and into the barrel chamber, and finally the breech is closed tight by rotating the handle down so the bolt head relocks on the receiver.
Bolt-action firearms are generally repeating firearms, but some single-shot breechloaders also use bolt-action design as a breechblock mechanism. The majority of these firearms are rifles, but there are some bolt-action variants of shotguns and handguns as well. Examples of these date as far back as the early 19th century, notably in the Dreyse needle gun. From the late 19th century all the way through both World Wars, bolt-action rifles were the standard infantry service weapons for most of the world's military forces. In modern military and law enforcement, bolt-action firearms have been mostly replaced by semi-automatic and selective-fire firearms, and have only remained prevalent as sniper rifles due to the design's inherent potential for superior accuracy and precision, as well as ruggedness and reliability compared to autoloading designs.