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