Microsoft Forefront Unified Access Gateway (Forefront UAG) is a tool that can provide a secure access option for remote end users who want to access corporate resources.
Forefront Unified Access Gateway 2010 (UAG) is the successor of Microsoft IAG (Intelligent Application Gateway). First introduced in 2010, Forefront UAG provides portal support and control mechanisms for security, including client authentication and application authorization.
Microsoft said it would discontinue Forefront UAG on July 1, 2014 but would provide mainstream support for Forefront UAG 2010 until 2015 and extended support until 2020.
See also: DirectAccess