American Airlines is introducing a low price guarantee on its website, offering a $50 voucher if customers find a lower fare than they find on AA.com (the offer is only good on domestic flights). Orbitz and Continental Airlines have offered similar deals, and hotel companies have had this for years (I was never a fan, though it’s difficult to determine how effective these guarantees are). Because of the changes in distribution deals over the past two years, domestic fares have become increasingly similar across websites (though this isn’t true for international fares, which is why they are excluded). Fare differences today stem from the ability of some websites (specifically, those powered by ITA Software, such as Orbitz) to find connecting flights that offer lower fares. Keep in mind, though, that this guarantee only covers customers finding lower fares for the same flights displayed on AA.com; the challenge sometimes occurs when you try to find the same routing on AA.com that you’ve found on Orbitz. In short, the guarantee makes for good press, but will not stop consumers from shopping around.