The Very Large Telescope Interferometer on Cerro Paranal in Northern Chile is one of the largest optical facilities used in astronomy. It can combine two or three of the four 8.2 m and four movable 1.8m telescopes, which span baselines between 8 and 202m. Observations are carried out in the near- and mid-infrared, covering the wavelength range from 1 to 13 μm.