The .308 Winchester (pronounced: “three-oh-eight” or “three-aught-eight”) is a rimless, bottlenecked, rifle cartridge and is the commercial cartridge from which the 7.62×51mm NATO round was derived. The .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62×51mm NATO T65. Winchester branded the cartridge and introduced it to the commercial hunting market as the .308 Winchester. Winchester’s Model 70 and Model 88 rifles were subsequently chambered for the new cartridge. Since then, the .308 Winchester has become the most popular short-action, big-game hunting cartridge worldwide. It is also commonly used for civilian target shooting, military sniping, and police sharpshooting. The relatively short case makes the .308 Winchester especially well-adapted for short-action rifles. When loaded with a bullet that expands, tumbles, or fragments in tissue, this cartridge is capable of high terminal performance. (Wikipedia)
Although very similar to the military 7.62×51mm NATO specifications, the .308 cartridge is not identical.