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Delta Air Lines on Tuesday introduced a "simplified" boarding system: Passengers will be divided into eight categories, based on the type of ticket they bought. Delta will start using the new boarding order on Jan. 23. It reflects Delta's efforts over the past six years to divide the economy cabin into even smaller classes of service, from a business-class-lite product with amenities kits and roomier seats, to bare-bones basic economy class.

Delta used to assign passengers one of six boarding zones, depending on how much they paid for a ticket and their frequent flyer status. Under the new system, which Delta says will "bring consistency, simplicity and clarity to the gate and boarding experience," travelers with tickets in its Delta One cabin, the airline's top service class for long-haul flights, or with top-tier frequent-flyer status will board first. They'll be followed by Delta's premium economy and first-class customers, then those with tickets for its extra-legroom Comfort+ seats in coach, and lower-tier frequent flyer elites. The remaining four groups will be coach-class passengers, with those with the no-frills basic economy tickets boarding last.