The "people who check your bags" fall into three distinct professional categories depending on where you are in the airport. First are the Check-in Agents or Passenger Service Assistants at the front counter; they are airline employees or contractors who weigh your luggage, verify your ID, and print the destination tags. Second are the TSA Officers (Transportation Security Administration) or their international equivalents, who work "behind the scenes" (or at the checkpoint for carry-ons) to scan bags for explosives or prohibited items using X-ray and CT technology. Finally, there are the Baggage Handlers (or Ramp Agents). These are the physically active crews who sort the bags after they disappear down the conveyor belt, load them into ULDs (Unit Load Devices), and drive them to the aircraft to be stacked in the cargo hold. While you rarely see the handlers or the TSA's deep-baggage scanners, these individuals are collectively responsible for ensuring your luggage is both safe to fly and reaches the correct destination carousel on the other end.