It is widely agreed that a 500 GeV e+e- linear collider, upgradeable to 1 TeV should be the next large scale project in particle physics. The design of such a machine is in progress and it could start data taking around 2017.
In this talk the ILC project will be briefly introduced and the physics case for this machine will be discussed in detail. Especially the complementarity to the LHC will be highlighted and it will be shown that the ILC is needed independent of the findings of the LHC.