A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.
This is a controversial amendment. Translated to modern English it means that the US government can't stop a state from forming a militia, and it can't take away citizen's armaments. This means that anyone in the US can own a gun (with the proper licensing). Citizens are allowed to own weapons to defend themselves, and the government can't take citizen's weapons.