The .30-06 is known for having high stopping power (meaning it does a lot of damage to a human or animal body), high penetration power (it can pierce through thick layers), and a long effective range (it is accurate for a long distance).
In the US military, it was the main bullet used for rifles and light machine guns for the first half of the 20th century. Guns that shot the .30-06 include the M1903 Springfield, the M1 Garand, the M1917, the M1919 Browning machine gun, and the BAR.
However, when the US created NATO, it replaced all the .30-06 military weapons with those that used the 7.62 x 51mm NATO bullet. This is because NATO requires the militaries of all its member countries to use the same kinds of ammunition.