The successful launch on November 17, 1995 of ESA's Infrared Space Observatory (ISO) by means of an Ariane 4 carrier, has set in motion a true revolution in quantitative infrared astronomy. For the first time since the very successful IRAS mission in 1983, the astronomical community has uninterrupted access to the infrared part of the electromagnetic spectrum. The four focal plane instruments on board of ISO ( the camera ISOCAM, the photometerjcamera ISOPHOT, and the short and long wavelength spec trographs ISO-SWS and ISO-LWS), perform very well and live up to the high expectations all of us...