However, a dreaded four-letter code—"SSSS"—could signal a significant slowdown in your airport security experience, with additional screening and bag searches. Here's everything you need to know.

You both notice the ominous "SSSS" on your boarding pass, a hiccup in your travel journey. But what happens next? What do those four letters mean, and how did they get on your boarding pass?

Commissions do not affect our editors' opinions or evaluations. An SSSS code on a boarding pass stands for “Secondary Security Screening Selection.” While somewhat annoying, this code only ...