"US-VISIT is a top priority for the U.S. Department of Homeland Security because it enhances security for our citizens and visitors while facilitating legitimate travel and trade across our borders. US-VISIT helps to secure our borders, facilitate the entry and exit process and enhance the integrity of our immigration system while respecting the privacy of our visitors. US-VISIT is part of a continuum of security measures that begins outside U.S. borders and continues through a visitors arrival in and departure from the United States. It incorporates eligibility determinations made by both the Departments of Homeland Security and State."
Department of Homeland Security: http://www.dhs.gov/