Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you flights up to 3 days before/after your preferred dates. That way, you can see if leaving a day or two earlier will find you a better deal. You can also select the flexible "weekend" or "month" search options to widen your search range and find the cheapest price that works for you.
KAYAK processes over 2 billion flight queries annually and displays results from hundreds of airlines and third party sites, allowing it to find a variety of flight prices and options. It also displays results from 2M+ properties along with rental cars, vacation packages, activities and millions of verified reviews so users can see as many available travel options as possible.