The Open Carry laws of Alabama underwent a major change, on of August 1st 2013. Previously only open carry of long guns was legal, now however if you have a permit to carry a concealed weapon it's legal for you to openly carry a handgun in public. The law states "It shall be a rebuttable presumption that the mere carrying of a visible pistol, holstered or secured, in public place, in and of itself, is not" disorderly conduct. Another article currently being debated by the Alabama legislature is AL code 13A-11-52, which says, "Except as otherwise provided in this article, no person shall carry a pistol about his person on premises not his own or under his control; but this section shall not apply to any sheriff or his deputy or police officer of an incorporated town or city in the lawful discharge of the duties of his office, or to United States marshal or his deputies, rural free delivery mail carriers in the discharge of their duties as such, bonded constables in the discharge of their duties as such, conductors, railway mail clerks and express messengers in the discharge of their duties." Open Carry in vehicles is illegal without a concealed weapons permit.
Open carry is the ability to carry a gun in plain view. Some states require a permit to open carry, and some do not, but most have restrictions on where it is legal to open carry.