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• United and JetBlue have announced a Blue Sky partnership. This will let passengers book flights for both carriers on each other’s websites and extend frequent-flyer redemption options. United will also return to JFK International Airport for the first time in 10 years.

On the surface, two airlines striking a partnership is a fairly common event. Code-sharing deals and airline alliances have been in place among several carriers for years. But the partnership announced Thursday by JetBlue and United Airlines is anything but typical.

The collaboration, called Blue Sky, will see the two airlines offer flights on each other’s websites, let customers comingle their frequent-flyer points, and allow United to return to New York’s JFK airport 10 years after it gave up its slots there.

What the heck is going on—and how does it impact passengers? Here’s what you need to know.

Are JetBlue and United Airlines merging?

No. JetBlue and United will remain separate companies, but are becoming much more closely aligned. JetBlue had hoped to purchase Spirit Airlines for $3.8 billion, but was blocked last year by a federal judge, saying it would harm competition. By striking a partnership, neither United nor JetBlue needs to seek the same degree of regulatory approval that they would for a formal merger.

Will this agreement change how I book flights on JetBlue and/or United?

You’ll still be able to book JetBlue flights through JetBlue and United through United, but you’ll also be able to book flights on United routes on JetBlue’s website and app and vice versa. Basically, you’ll have expanded options on both carriers’ websites and apps (much as you do on third-party sites like Google Flights and Expedia).

This partnership is not a code-sharing agreement, however. Each airline will publish and market flights independently under its own brand and flight numbers. Additionally, the two carriers will not coordinate their schedules or share revenue.

What’s the impact on JetBlue’s and United’s frequent-flyer programs?

You’re going to have a lot more options on where you can go. United’s MileagePlus customers will be able to earn and use miles on most JetBlue flights (and JetBlue TrueBlue members can use their points on United flights). That will give United frequent flyers more access from the Northeast to the Caribbean—and JetBlue members will have a slew of international destinations made available to them.

Your perks will remain the same on both airlines. For instance, if you’re a Mosaic 2 member in JetBlue’s frequent-flyer program, you’ll board with group one on United flights (and get priority check-in, same-day changes, and other benefits). Premier Gold members with United will board with Group B on United flights. (See here for a full list of reciprocal benefits.)