Modern airport security utilizes a suite of advanced technologies to screen passengers and luggage, with three primary types being Millimeter Wave Scanners, Computer Tomography (CT) Scanners, and Explosive Trace Detection (ETD) systems. Millimeter Wave Scanners are the "body scanners" that passengers stand inside; they use non-ionizing radio waves to create a 3D image of the body to detect hidden objects without emitting harmful radiation. CT Scanners are the latest generation of carry-on bag X-rays; they take hundreds of images to create a 3D view of a bag’s contents, allowing security to virtually "rotate" the bag and even identify liquids, which is why some airports no longer require you to remove your laptop. Finally, ETD systems involve "swabbing" a passenger's hands or luggage; the swab is placed into a machine that analyzes the particles for microscopic traces of explosive chemicals, providing a final layer of defense against high-tech threats that visual scanners might miss.