If you spot “SSSS,” get ready for another screening.

Mehroz Kapadia/Travel + Leisure

Airport security is an important system that maintains the safety of the public.

Here’s everything it’s crucial that you know.

An illustration of a boarding pass and passports over a world map

Credit:Mehroz Kapadia/Travel + Leisure

What is SSSS?

SSSS stands for Secondary Security Screening Selection by theU.S.

Department of Homeland Securityand is displayed on boarding passes as a four-letter code.

The symbol prompts officers to conduct additional security screenings on a passenger.

The additional screening is part of the federal governments layered security approach at commercial airports.

What should you do if you get SSSS multiple times?

Once your case is reviewed, successful applicants will be given aredress numberto add to future airline bookings.

Are there other reasons for extra security screenings?

“Sometimes, that behavior can be connected to drug smuggling.