A .308 rifle is a rifle that is made to fire the .308 Winchester cartridge. This can be a bolt action rifle, semi-automatic rifle (such as a modern sporting rifle), or a break barrel rifle. When you generally refer to a rifle as a “.308 rifle”, it is not descriptive in who manufactures the rifle, the design of the rifle, or any other rifle characteristics, except the fact that the rifle is chambered in .308 Winchester.
When the .308 Winchester came out, it was considered to be the “snipers round” due to its impressive ballistics and the fact that it was fairly flat shooting. This made the round wildly popular, and nowadays it is considered by many to be the standard round for hunting big game in North America. While some newer cartridges outperform the .308, its popularity, rock solid performance, and established place in the manufacturing world ensure that this cartridge will be around for a very long time.