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.

Frontier Airlines is introducing a free checked bag promotion in an effort to poach former Southwest passengers frustrated by the airline's decision to ditch its longstanding "bags fly free" policy. Called "Your New Love,

Frontier Airlines announced on Tuesday that it would fly your bags for free on select flights in an effort to be your “rebound” if you’ve been scarred by the end of Southwest’s policy. Here’s how it works.