Portal 2 maker Valve has officially launched Steam Guard.
Steam Guard, which had been in beta, blocks any attempt to access a protected account from an unrecognised computer and is designed to add a layer of protection to your games.
It works by sending a verification email to the your registered email address that must be actioned should a computer attempt access.
Steam Guard is so secure, Valve boss Gabe Newell confidently shared his Steam password to a crowd at the Game Developers Conference.
There's more information over at Valve's Steam Guard FAQ.