Check your boarding pass: If the letters SSSS are on it, expect to spend extra time at security. Here's what triggers SSSS on a boarding pass.

A boarding pass contains a lot more information than just your gate and seat number. Boarding passes include codes that identify details about passengers and their itineraries.

The code "SSSS" on a boarding pass stands for "Secondary Security Screening Selection," requiring additional screening at TSA checkpoints. Reasons for the "SSSS" code can include last-minute ...

But your boarding pass contains a lot more than just your plane seat and gate number. It also includes codes that communicate details about passengers and their itineraries to airport staff.