Virtual observatory (VO) is a collection of interoperating data archives and software tools which utilize the internet to form a scientific research environment in which astronomical research programs can be conducted.
In much the same way as a real observatory consists of telescopes, each with a collection of unique astronomical instruments, the VO consists of a collection of data centres each with unique collections of astronomical data, software systems and processing capabilities.
The main goal is to allow transparent and distributed access to data available worldwide. This allows scientists to discover, access, analyze, and combine nature and lab data from heterogeneous data collections in a user-friendly manner.
The IVOA (International Virtual Observatory Alliance) is a standards body created by the VO projects to develop and agree the vital interoperability standards upon which the VO implementations are constructed.