Southwest Airlines will begin charging customers a fee to check bags. It's a significant change for the budget carrier, which built years of advertising campaigns around its policy of letting passengers check up to two bags for free.

The carrier announced Tuesday that it will begin charging certain passengers to check their luggage on flights, a significant shift at the company long prized by consumers for its perks.

Dallas-based Southwest Airlines made an unexpected announcement: it would be doing away with its bags fly free policy. The policy allowed passengers' first two checked bags to fly free and has been a hallmark of the alternative airline since its founding nearly 60 years ago.