Summary of Special Session 3

The Virtual Observatory is one of the very few truly global endeavours of astronomy, and IAU General Assemblies are the natural places to present the VO to the community. The three-year time scale of IAU is also well suited to measure progress. At the IAU XXV GA in Sydney, 2003, half of the two-day Joint Discussion 8 on Large Telescopes & Virtual Observatories: Visions for the Future was devoted to VO talks: the main goal was to review what was expected from the VO in different disciplines of astronomy; many projects were also presented in the poster sessions. This time the three-day VO Special Session has given an excellent overview of present status of the VO, showing both tremendous progress and the work which remains to be done. Several scientific communities (astronomy, solar and heliospheric physics) are working on VO development, national communities have been organizing themselves in VO projects. Implementation by data centres has begun. Additional technical development is required, and there are still technical challenges. There is also a huge work ahead for providing high quality data and services, but the VO development already has a very positive influence on astronomers' work environment, and more is to come.