The International Space Station is a joint effort between many nations of earth to build a permanent space station in earth orbit from whence we can carry out much more elaborate scientific experiments, and the most probable location for the first permanent commercial manned presence in space. This station may well be the key to mankind's future in space. Once space becomes a place for commercial interests, access will become MUCH cheaper.
The first module of the International Space Station was launched on November 20th, 1998.
Time Line of ISS Launch and Construction