When you book airline tickets on Kayak, you’re sent to the airline’s website to complete your booking. This makes it safe to buy airline tickets on Kayak because you’re actually booking directly with the airline. So if you want to book a flight with United Airlines on Kayak, clicking on the deal will send you to the United website where you can input your credit card information and complete the booking there. Similarly, cancellations and flight status will be handled through the airline with which you booked as well.