Kayak was launched by Orbitz, Travelocity and Expedia co-founders.
Kayak is not a travel agency, but a travel search engine or a metasearch site. The company does not sell airline tickets or hotel rooms or rental car reservations. Instead, it directs consumers to other travel sites where they can make these purchases directly.
By using Kayak you can save a considerable amount of time and money. Instead searching through dozens of travel sites yourself, while trying different combinations of dates, airports, and airlines, on Kayak you can simply fill out one search form and let the site do all the work for you. In a matter of seconds, Kayak will search hundreds of sites and will present you with clickable results.
Major airlines such as United, American, Delta, Lufthansa, Air France, British Airways, KLM Royal Dutch, SAS, and so forth are included, as well as such travel sites as Orbitz, Airfare, and Cheaptickets.
Another advantage of Kayak is its ability to do searches on your behalf and notify you when the best deals are found according to the preferences you've provided. Unlike other sites, your preferences can be rather flexible.
For example: You would like to fly from Charlotte, NC (CLT) to St. Petersburg, Russia (LED) in the fall and would like the max price to be below $900. If there are currently no deals according to your search parameters, then as soon as the deals are found, you will receive a notification in your e-mail. You may also supply other options, such as nearby airports: Raleigh/Durham, NC (RDU) or Greensboro, NC (GSO); your date range in days, weeks or even months; etc. All you have to do is register and enter your search preferences, then sit back and relax while everything else is done by Kayak.