The .308 Winchester -- aka: 7.62 NATO

The .308 Winchester was introduced by Winchester (duh) in 1952 and within 5 years received a huge benefit by being adopted as the NATO-standard rifle and light machine gun calibre. The other NATO countries were looking at smaller calibres, but the USA was the "Big Dog In The Fight" and insisted on a "full-power .30 calibre rifle cartridge." In about 10 years the USA would reconsider. The two cartridges are not 100% identical but they are interchangeable -- at least that's what the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) says.
From 1957 onward the .308 has been as popular as almost all other cartridges adopted by major militaries. That's a BIG boost in popularity.

The .308 was developed as a cartridge that would work in rifles with shorter actions than the usual .30-'06 rifles. For some reason this was seen as desirable. It was desired to have .30-'06 performance (or nearly so) out of a shorter cartridge case. The .308 case is 12 mm (about one-half inch) shorter than the .30-'06. The .308 never matched the old .30-'06 in power, but it did come close. How close is actually rather surprising. It is a rimless, bottle-necked case loaded with .308" diameter bullets.

It is a good hunting cartridge. With the right bullet selection it can even be used for moose, though most hunters think that it is a little light for that. It has been chambered in just about every type of rifle in existence as well as many light and medium machine guns. Winchester actually made a rimmed version of the .308 loaded with flat-point bullets and called it the .307 Winchester for use in the Winchester model 94 lever-action rifle. Ammunition is as plentiful as any, and there is still relatively cheap military surplus ammo to be had.

If you are looking for a good all-around hunting cartridge there aren't many better than the .308 -- unless you live in Africa!