An airline is a company that provides air transport services for traveling passengers and freight. They utilize aircraft to supply these services, and may form partnerships or alliances with each other for codeshare agreements. Generally, airline companies are recognized with an air operating certificate or license issued by a governmental aviation body. Also, they vary in size, from small domestic to full-service international airlines with double-decker airplanes. Airline services can be categorized as being intercontinental, domestic, regional, or international, and may be operated as scheduled services or charters. The largest airline currently is American Airlines Group. The First DELAG was the world's first airline. It was founded on November 16, 1909, with government assistance, and operated airships manufactured by The Zeppelin Corporation. Its headquarters were in Frankfurt. The first fixed-wing scheduled airline was started on January 1, 1914, from St. Petersburg, Florida, to Tampa, Florida, operated by the St. Petersburg and Tampa Airboat Line. The four oldest non-dirigible airlines that still exist are Netherlands' KLM (1919), Colombia's Avianca (1919), Australia's Qantas airline (1921), and the Czech Republic's Czech Airlines (1923) The world's largest airlines can be defined in several ways. American Airlines Group is the largest by its fleet size, revenue, profit, passengers carried and revenue passenger mile. Delta Air Lines is the largest by assets value and market capitalization. Lufthansa Group is the largest by number of employees FedEx Express by freight tonne-kilometers Ryanair by the number of international passengers carried Turkish Airlines by the number of countries served.