Overview#REAL ID or Real ID Act of 2005, Pub.L. 109–13, 119 Stat. 302, enacted May 11, 2005, is an Act of United States Congress that modifies United States Federal Law pertaining to security, authentication, and issuance procedures standards for state Driver License and identity documents, as well as various immigration issues pertaining to terrorism.
REAL ID law sets forth requirements for US State Driver License and ID cards to be accepted by the United States federal government for "official purposes", as defined by the Secretary of the United States Department of Homeland Security. The Secretary of Homeland Security has defined "official purposes" as boarding commercially operated airline flights, and entering federal buildings and nuclear power plants, although the law gives the Secretary the unlimited authority to require a "federal identification" for any other purposes.
Ldapwiki refers you to Wikipedia: United States Federal