The Transportation Security Administration (TSA), within the Department of Homeland Security, screens or oversees the screening of more than 650 million air passengers annually at more than 450 airports nationwide, and attempts to balance its aviation security mission with the freedom of movement for people and commerce. In 2011, TSA began developing new security procedures intended to strengthen security and improve the passenger experience by shortening lines and wait times. These new procedures apply risk-based, intelligence-driven screening concepts and enhance the use of technology to determine passenger risk prior to travel. These procedures are intended to allow TSA to devote more time and resources at the airport to screening the passengers TSA determines to be higher or unknown risk while providing expedited screening to those passengers TSA determines pose a lower risk to the aviation system. According to TSA, expedited screening involves a relatively more efficient and convenient screening process for individuals from whom TSA has obtained sufficient information to determine them to be lower risk, compared with the standard screening process for a traveler for whom TSA does not have such information. For example, passengers eligible for expedited screening may no longer have to remove their shoes; may leave their permitted liquids, gels, and laptops in carry-on baggage; and are not required to divest light outerwear, jackets, or belts when passing through screening checkpoints unless the walk-through metal detector alarms, in which case these items must be removed.