SpaceX has developed three launchers so far. The Falcon 1 was a developmental model, used mainly for testing. Falcon 1 was first launched in 2006. Two of its five launches were a success and the model is now retired. The Falcon 9 is a 333 ton launcher that can lift ten tons into orbit and is competitive with the older (government developed) Delta IV and the Atlas V launchers. Falcon 9 first launched in 2010, and entered service this year. The Falcon Heavy is still in development and will lift commercial and military cargoes. Falcon Heavy is a development of the Falcon 9 and will fly for the first time next year.
SpaceX offers lower prices and more flexibility than most government (usually military) developed launchers. As a privately owned company SpaceX has less bureaucracy and is quicker to adapt new technology for launch services. Many existing and potential SpaceX customers see this as the future of space transportation.