DirectAccess allows remote users to securely access enterprise shares, websites, and applications without connecting to a virtual private network (VPN). DirectAccess establishes bi-directional connectivity with a user’s enterprise network every time a user’s DirectAccess-enabled portable computer connects to the Internet, even before the user logs on. Users never have to think about connecting to the enterprise network and IT administrators can manage remote computers outside the office, even when the computers are not connected to the VPN.

(From TechNet)