Expedia.com is an Internet-based travel agency and a part of Expedia, Inc.. It books airline tickets, hotel reservations, car rentals, cruises, vacation packages, and various attractions and services via the World Wide Web and telephone travel agents. The site uses the Sabre (computer system) and formerly Worldspan as their main Computer reservations system(s), with the adjuncts of Pegasus and their own Canadian connectivity company for hotels that are not listed in Worldspan. In 2006, Expedia.com was awarded a Webby Award in the area of "Best In Travel Websites" a Stevie Award from the American Business Association for "Most Innovative Company" as well as the top rating in customer satisfaction across online travel agencies by the American Customer Satisfaction Index.

A travel agency is a business that sells travel related products and services, particularly package tours, to end-user customers on behalf of third party travel suppliers, such as airlines, hotels, tour companies, and cruise lines. In addition to dealing with ordinary tourists, most travel agents have a special department devoted to travel arrangements for business travelers, while some agencies specialize in commercial and business travelers. Some agencies also serve as general service agents for foreign travel companies in different countries.

The British company, Cox & Kings is sometimes said to be the oldest travel agent in the world, but this rests upon services that the original bank (established in 1758) supplied to its wealthy clients. However, the modern travel agent first appeared in the second half of the nineteenth century. Thomas Cook, in addition to developing the package tour, established a chain of agencies in the last quarter of the nineteenth century, in association with the Midland Railway. These not only sold their own tours to the public, but represented other tour companies. Other British pioneer agencies were Dean and Dawson, the Polytechnic Touring Association, and the Co-operative Wholesale Society.

Travel agencies became more commonplace with the development of commercial aviation starting in the 1920s. Originally, the agencies largely catered to middle-class customers, but the post-war boom in mass-market package holidays resulted in travel agencies on the main streets of most British towns, catering to a working class clientèle looking for a cheap overseas beach holiday.