The goal of ASTERICS WP4 (Data Access, Discovery and Interoperability) was to ensure that the ESFRI products become openly accessible via the Virtual Observatory framework to the international community. Training activities to efficiently use these new resources was identified as one of the important objectives within this work package. In this context, four Virtual Observatory (VO) schools were organised with a twofold objective:

- Expose European astronomers (in particular early-career people) to the variety of VO tools and services available today so that they can use them efficiently for their own research.

- Gather feedback and requirements from this intense and diverse usage.

During the schools, VO experts guided the participants on the usage of VO tools through a series of tutorials built based on real life science cases. Participants also had the opportunity to develop their own science cases.

One hundred and thirty-six participants from 16 different European countries attended the schools. Feedback gathered from participants demonstrated that the goals of the schools were fulfilled and that they were efficient steps forward in the process of building an astronomical VO community both within ASTERICS and beyond the project's borders across Europe.