The simplicity of the initial state and the cleanliness of the experimental environment are the key arguments for an e+e- collider. The ILC is a 500 GeV linear collider that has been planned over the past decade in a global effort. While a possible extension to TeV centre of mass energies has always be foreseen the operation at lower energies has recently gained more attention. Depending on the experimental findings at the LHC over the remainder of this year an operation mode known as a Higgs factory may be particularly interesting. In fact, such a Higgs factory has even been proposed to be realized in a circular collider in the LEP/LHC tunnel.
The talk will address the key accelerator physics issues and give the current status of the project.