TSA PreCheck
What It Does: Expedites the security screening process at major U.S. airports.
How It Works: Membership provides two primary benefits when you pass through security at a U.S. airport or foreign airport with U.S. preclearance:
The major benefit is access to a dedicated screening lane.
A minor benefit is that you need not remove your shoes, light outerwear, or belt during screening and you don't need to take your 3-1-1 bag of liquids or your laptop from your carry-on (although, if the airport uses magnetic rather than radio screening, you still may have to ditch any shoes, belts, or clothing items with metal buttons or fixtures).
The system operates through airlines. You do not get any ID card; instead, you notify your airline of your membership and the airline automatically prints a TSA PreCheck code on your boarding pass. The easiest way to handle this is to enter your eligibility number through your frequent-flyer program, from which the airline can extract the data any time you fly. For details, check here.
Where It Works: TSA PreCheck is airline-based.
Eligibility: U.S. citizens currently enrolled in CBP's Global Entry, Sentri, or Nexus programs are automatically eligible to participate in TSA PreCheck, as are Canadian citizens who are members of Nexus. Also, active-duty military personnel can use the TSA PreCheck system at a handful of airports by identifying themselves at the security entry point.
Enrollment: If you haven't entered TSA PreCheck through your airline, you can get in by signing up for Global Entry, Sentri, or Nexus. TSA has also announced that it will offer some degree of expedited clearance based on just the limited personal information you supply to the airline when making your reservation. But this won't be as good as the benefits that full members receive.