The XENON100 experiment aims to detect cold dark matter particles via their
collisions with xenon nuclei. An ultra-low background, two-phase time projection
chamber with a total of 170 kg of xenon (70 kg in the target region and 100 kg
the active shield) has been installed at the Gran Sasso Underground Laboratory
is currently in commissioning phase. I will review the design and performance of
detector and its associated systems, based on initial calibration runs.