The emergence of the three-dimensional structure of the cosmic web over
the history of the Universe displays very distinctive features when
observed in X-rays, where both the most massive collapsed structure
(clusters of galaxies) and the most energetic events in the life of
galaxies (AGN and Quasars) reveal themselves unambiguously. The next
generation of wide-area, sensitive X-ray surveys designed to map the hot
and energetic Universe will be heralded by eROSITA (extended ROentgen
Survey with an Imaging Telescope Array), the core instrument on the
Russian-German Spektrum-Roentgen-Gamma (SRG) mission, successfully
launched in July 2019. The high sensitivity, large field of view, high
spatial resolution and high survey efficiency of eROSITA is bound to
revolutionize X-ray astronomy and deliver large legacy samples for many
classes of astronomical objects in the energy range 0.2-8 keV. I will
present an overview of the instrument capabilities, the current status
of the mission, a few selected early science results and the
expectations for the survey program, which has completed in June the
first observation of the whole sky.