Once selected, the traveler usually goes through extra screening beyond the normal security process. This may include a more detailed pat-down, a full search of carry-on bags, swabbing items for explosive traces, and checking that electronic devices can turn on properly.
The process can feel stressful or embarrassing because it happens in a busy airport and may cause delays. The best response is to stay calm, arrive early, keep bags organized, and cooperate politely so the screening can be completed as smoothly as possible.
For people who get SSSS repeatedly, it may be due to a mistaken identity or a name similar to someone on a watchlist. In that case, applying for a DHS Redress Number can help reduce repeated extra screenings and make future travel easier.