In this symposium on Wolf-Rayet stars, binary aspects received ample attention, notably because of the recognition that many observations of spectral and photometric variability at all accessible wavelengths are related to colliding winds or other forms of wind interaction. The basic structure of the conference and its proceedings is: basic parameters and general properties of WR stars; state of the art model atmospheres for WR stars, anisotropic mass loss and disk formation of WR stars, properties of WR binaries; influence of stellar winds on mass transfer in hot massive binary evolution; dust formation near WR stars and other circumstellar phenomena; and hydrodynamics and high-energy physics of colliding winds in WR+O binaries and of WR winds interacting with compact objects. Within this framework 20 invited reviews, 38 invited oral contributions, and 76 poster papers were presented at the Symposium, entertaining 111 astronomers from 24 countries. These proceedings provide up-to-date information on all aspects of Wolf-Rayet atmospheres, binaries, and colliding winds.

The first ideas for the symposium were generated in Brussels in the summer of 1986, dur ing exquisite lunches in between HST proposal consortium meetings. At the time it was expected that soon after the previous IAU symposium (No. 116) devoted to luminous hot massive stars, a bonanza of new exciting observational material would become available, together with significant advances on the theoretical front. Also it was felt that Wolf Rayet stars should feature predominantly, because that had not been the case since IAU Symposium No. 99 in 1981. Tradition requires that IAU symposia on hot massive stars take place in high lumi nosity beach resorts, and after Buenos Aires, Qualicum Beach, Cozumel and Porto Heli, Bali sounded like a reasonable place. Therefore we were only too pleased with the invitation of the Indonesian astronomical community to host the symposium in Sanur (Denpasar). The aim of the symposium was to bring together both observers and theoreticians active in the field of Wolf-Rayet stars and related objects, to present and discuss their recent results, in order to expose to what extent consensus exists as to the physical and chemical properties of Wolf-Rayet stars, their evolutionary status and their interrelations with other massive stars in galaxies."

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 had at launch. In the spring of 1996, Thijs de Graauw (principal investigator of the SWS) first suggested the idea to organize a conference dedicated to ISO re sults in the area of stars and circumstellar matter, and coined the title ISO 's View on Stellar Evolution. At the first scientific meeting to highlight some of the early ISO results which was held in May of 1996 at ESA's laboratory ESTEC in Noordwijk, the Netherlands, the conference was announced and a preliminary science organizing committee was formed. The conference was held from July 1 to 4, 1997, in conference centre de Leeuwenhorst, Noord wijkerhout, the Netherlands. The conference was opened by the Director of ESA 's Science Programme, Professor R. Bonnet."

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 had at launch. In the spring of 1996, Thijs de Graauw (principal investigator of the SWS) first suggested the idea to organize a conference dedicated to ISO re sults in the area of stars and circumstellar matter, and coined the title ISO 's View on Stellar Evolution. At the first scientific meeting to highlight some of the early ISO results which was held in May of 1996 at ESA's laboratory ESTEC in Noordwijk, the Netherlands, the conference was announced and a preliminary science organizing committee was formed. The conference was held from July 1 to 4, 1997, in conference centre de Leeuwenhorst, Noord wijkerhout, the Netherlands. The conference was opened by the Director of ESA 's Science Programme, Professor R. Bonnet.

In this IAU Symposium on Wolf--Rayet stars, binary aspects received ample attention, notably because of the recognition that many observations of spectral and photometric variability at all accessible wavelengths are related to colliding winds or other forms of wind interaction. The basic structure of the conference and its proceedings is basic parameters and general properties of WR stars; state of the art model atmospheres for WR stars, anisotropic mass loss and disk formation of WR stars, properties of WR binaries; influence of stellar winds on mass transfer in hot massive binary evolution; dust formation near WR stars and other circumstellar phenomena; and hydrodynamics and high-energy physics of colliding winds in WR+O binaries and of WR winds interacting with compact objects. Within this framework 20 invited reviews, 38 invited oral contributions, and 76 poster papers were presented at the Symposium, entertaining 111 astronomers from 24 countries. These proceedings provide up-to-date information on all aspects of Wolf--Rayet atmospheres, binaries, and colliding winds.

The first ideas for the symposium were generated in Brussels in the summer of 1986, dur ing exquisite lunches in between HST proposal consortium meetings. At the time it was expected that soon after the previous IAU symposium (No. 116) devoted to luminous hot massive stars, a bonanza of new exciting observational material would become available, together with significant advances on the theoretical front. Also it was felt that Wolf Rayet stars should feature predominantly, because that had not been the case since IAU Symposium No. 99 in 1981. Tradition requires that IAU symposia on hot massive stars take place in high lumi nosity beach resorts, and after Buenos Aires, Qualicum Beach, Cozumel and Porto Heli, Bali sounded like a reasonable place. Therefore we were only too pleased with the invitation of the Indonesian astronomical community to host the symposium in Sanur (Denpasar). The aim of the symposium was to bring together both observers and theoreticians active in the field of Wolf-Rayet stars and related objects, to present and discuss their recent results, in order to expose to what extent consensus exists as to the physical and chemical properties of Wolf-Rayet stars, their evolutionary status and their interrelations with other massive stars in galaxies."