The ISS is a research facility and the successor to the Mir space station, which was in operation between 1983 and 1998 before being sunk in the Pacific Ocean in a "spacecraft cemetery" not far from Christmas Island in 2000.
The agreement to construct the ISS was signed January 29, 1998 in Washington by representatives from Canada, members of the European Space Agency (ESA), Japan, Russia and the United States.
The first launch as part of the project took place on November 20, 1998 from Baikonur space center in Kazakhstan, when a Russian Proton space carrier delivered the Zarya unit, which was the station's first component.
Two weeks later on December 4, 1998, the U.S. shuttle Endeavour delivered the second Unity module, which docked with Zarya on December 6. Both units were connected on July 26, 2000 with the Zvezda module, which was delivered earlier in the year by a Russian Proton carrier rocket.
The station only became manned on October 31, 2000, when Russia delivered the 1st ISS crew, which included American astronaut William Shepherd and two Russian astronauts Yury Gidzenko and Sergei Krikalev.
The ISS has continued to expand and develop with the addition of the Italian-made Harmony Node 2 module in October 2007. The module is designed to expand the ISS interior to around 18,000 cubic feet and allow European and Japanese research laboratories to be connected to the space station in the future.
Russia plans to add a further three modules, including a lab module, to its segment by 2011 and new energy modules are planned to be added later.
To date a total of 144 astronauts have visited and worked on the ISS, including 15 permanent and 13 visiting expeditions. The ISS 16th expedition, comprising two U.S. astronauts Peggy Whitson and Daniel Tani and Russia's Yury Malenchenko, are currently on board.
In addition to the various scientific experiments carried out on board the ISS, the research facility has also received a number of space tourists.
Dennis Tito, an American businessman and former NASA scientist, became the world's first space tourist when he spent a week on the ISS in 2001.
He was followed by South African computer millionaire Mark Shuttleworth in 2002, and Gregory Olsen, a U.S. entrepreneur and scientist, in 2005.
In 2006 the space station received its first female space tourist, businesswomen Anousheh Ansari, 40, a U.S. passport holder of Iranian origin.
Last year Charles Simonyi, 58, a U.S. national of Hungarian descent and a key figure in developing Microsoft's Word and Excel applications spent a week on the ISS.
This year the station will receive its sixth space tourist, who is U.S. computer games developer Richard Garriott.
The ISS today is the largest project implemented jointly by Russian Space Agency Roscosmos, America's National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), the Canadian Space Agency (CSA) and Japan Aerospace Exploration Agency (JAXA).