Have you ever noticed a string of letters or numbers on your boarding pass that your fellow travelers seem to be missing?

Along with your name and seat number, your boarding pass will often include some personal and flight information in various codes. That can get confusing, especially on top of several recent changes in airport policy.

Milwaukee Mitchell International Airport on Tuesday, June 20, 2023, provide many interesting places to check out while waiting for your flight such as Renaissance Books and the Summerfest Marketplace.

Here's what to know about boarding pass codes and the newest airport policies if you're traveling this summer:

What do the letters and numbers on your boarding pass mean?

SSSS: Secondary Security Screening Selection. Perhaps one of the most-recognized codes, "SSSS" means a passenger must undergo additional security screening. That can include a pat-down, luggage search or extra questioning by TSA officers.
PNR: Passenger Name Reference. This is a series of numbers and letters, unique to each passenger and used to identify their basic flight and personal information.
ET or ETKT: Electronic Ticket. Some airlines use this code, instead of a PNR, to pull up a passenger's flight itinerary.
FQTV: Frequent Traveler. This means the passenger is a part of the airline's frequent traveler program.
SEQ or SEQ NO: Sequence number. This code indicates your spot in the boarding order.
BCBP: Bar-Coded Boarding Pass. This is the bar code that gate agents will scan as you board the plan.
S/O: Stopover. This means the flight has a layover in one or more airports.
SPTC: Stopover Paid by the Carrier. This means the layover is longer than a few hours and, in some case, the airline may include overnight accommodations as a result.

Should you throw away a boarding pass after a flight?

If you're using a paper boarding pass, travel officials and security experts advise against throwing away your pass as is after the flight. Scammers can use the personal information on boarding passes to access your accounts.

Instead, you should shred your boarding pass before discarding it, or use an electronic one.

What are the recent changes to airport policy? Real ID, TSA

You need a Real ID for domestic travel

Perhaps the biggest change to air travel has been the implementation of the long-delayed Real ID.

As of May 7, you need a Real ID to fly domestically. It's worth noting you can still travel if you haven't gotten one, but you'll need a TSA-approved alternative — like a U.S. passport — to do so.

You can't bring lithium-ion batteries in checked bags

Not sure if something uses this kind of battery? Here are some common items:

Power banks
Cellphone battery charging cases
Rechargeable and non-rechargeable lithium batteries
Cellphone batteries
Laptop batteries
External batteries
Portable rechargers

You don't have to remove your shoes for security anymore

This article originally appeared on Milwaukee Journal Sentinel: Flying to or from Wisconsin? Don't toss your boarding pass right away, officials say