Many airlines and travel web sites (such as Expedia, Kayak, etc.) track how many times you’ve visited their websites. In so doing, they provide different offers and deals depending on the user.
To make sure you’re getting the best prices when you book air travel online, be sure to clear your web browser’s cookies and cache. This will make it appear as if it’s your first time visiting these sites, and you’re likely to see much better prices for your next flight!