Delta Air Lines announced this week that it would soon begin offering five new kinds of “products” -- or what we used to call seats.

Warning: These products are a mouthful. You start with the familiar Main Cabin and First Class — easy enough. Then you have Delta Comfort+, a just-created middle realm with extra legroom. The lair known as Delta One luxuriates in the front of the aircraft, secluded behind several curtains.

And Basic Economy? That's way in the back, where the usual flying experience is stripped of anything that could possibly make it convenient.

For decades, airplane seats were a fairly uncomplicated species. There was first class, and everything else. But an airline industry pushing for new ways to make profits is now reconsidering that convention and others.

With its new seating tiers, Delta is taking perhaps the most aggressive step among U.S. carriers to segment its own planes, competing both for business and budget travelers and everything in between.

Some analysts say the move is well-conceived, giving customers the same top-to-bottom choices they have when shopping, say, for a car or a watch.

But many are more skeptical -- and fear the changes will simply make flying more expensive. Delta already earns more than other U.S. carriers on baggage fees and ticket change fees, and changing the seating system opens up a new rationale for charges. If you want no amenities, pick the Basic seats. But if you want meals or alcohol or in-flight entertainment or a few extra inches of legroom, you’ll be paying more.

Overall, economy fliers do have more options these days, with the surge in popularity of budget airlines like Frontier and Spirit. Delta’s strategy has likely been shaped in part by those competitors.

They aren’t Spirit, of course, but at least some seats — Delta hasn’t said how many — will have parts of the Spirit experience. Those who purchase Basic Economy tickets won’t be able to select seats in advance. They also aren’t entitled to changes, refunds or upgrades.

“The legacy airlines are learning tricks from the Frontiers and Allegiants and the Spirits,” said Tom Parsons, who runs the Web site “Every part of the service is becoming a la carte.”

No single Delta flight will have five seating tiers at once. Delta One, with the sleeper pods and Westin bedding, is only available on long-haul international flights. And Basic Economy is only available on some domestic routes — notably in markets in which Delta competes with Spirit.

Delta hasn’t indicated the price differences between the various tiers. The roll out is scheduled to begin March 1.