Airlines are flying almost full—and so are the airports’ VIP lounges.

Not long ago, airport lounges were very desirable places to be. They were quiet, luxe areas with snacks.

Lounges offered a place to relax, work, and entertain friends or business associates between or before flights.

Passengers could either pay a few hundred dollars a year for their memberships, or they could gain entrance through a combination of elite status or carrying particular credit cards.

But now those alternate pathways to lounge entrance are being cut. Even a day pass at many airline lounges will run you $50.

However, there are still some ways to get into airport lounges.

Make friends. Remember: membership at an airline lounge allows you to bring in at least one guest.

United Airlines Mileage Plus Explorer Card gets you into its lounge.

The American Express Platinum card gets you into more than 600 lounges worldwide.

Yes, there’s even an app. It’s called Lounge Buddy, and it locates lounges and lets you know which card in your wallet will open that door.

For more information about airlines and airports, check out:

• The Busiest Airports in the World
• New Options for Flying From the U.S. to Europe
• Just How Clean Are Airplanes and Airports?

Keep reading for more travel tips.