Science opportunities on the VLT Interferometer

The VLTI is in science operations since several years, with new opportunities becoming available 
every time new facilities are being integrated. Most of these steps are easily visible, but some  
possibilities arise from simple improvements. I will detail the scientific potential of the VLTI, 
giving an overview about both the modes offered by the instruments, limitations set on sky 
accessibility, object flux over the visible and infrared spectrum, or object morphology. I will 
close with a detailed discussion of what information can be extracted from VLTI measurements.