Air travel blends excitement with stress, from planning routes to navigating crowded airports. Even experienced travelers juggle schedules, documents, and strict rules, making the process mentally demanding from start to finish.

Amid this complexity, some passengers notice an unusual code on their boarding pass: “SSSS.” It often appears without warning, causing confusion or concern when additional screening begins unexpectedly.

“SSSS” stands for Secondary Security Screening Selection, a designation used by the Transportation Security Administration. It means the traveler has been chosen for extra security checks before boarding.