A carbine is a firearm similar to, but generally shorter and less powerful than, a rifle or musket of a given period. There have been many carbines developed from rifles, being essentially shorter rifles firing the same ammunition, although usually at a lower velocity, and there have also been many where the carbine and rifle adopted by a particular nation were not technically related, such as using completely different ammunition or internal operating systems (though the carbine still being weaker, or of smaller size). Which may be more common, depending on the time period.
In the 1800s, carbines were generally smaller firearms for cavalry. The foot soldiers would have a longer, more powerful firearm, and cavalry a shorter, lighter firearm. The shorter length and lighter weight of carbines makes them easier to handle in close-quarter combat situations (such as urban or jungle warfare), or when deploying from vehicles. The disadvantages of carbines, when compared with their longer counterparts, are generally poorer long-range accuracy and shorter effective range.