Airport security refers to the techniques and methods used in protecting airports and aircraft from crime.
Large numbers of people pass through airports. Such gatherings present a target for terrorism and other forms of crime due to the number of people located in a small area. Similarly, the high concentration of people on large airliners, the potential high lethality rate of attacks on aircraft, and the ability to use a hijacked airplane as a lethal weapon provide an alluring target for terrorism.
Airport security provides defense by attempting to stop would-be attackers from bringing weapons or bombs into the airport. If they can succeed in this, then the chances of these devices getting on to aircraft are greatly reduced. As such, airport security serves two purposes: To protect the airport from attacks and crime and to protect the aircraft from attack.