ESPRESSO, the VLT rocky exoplanets hunter, will combine the efficiency of modern echelle spectrograph with extreme
radial-velocity precision. It will be installed at Paranal on ESO's VLT in order to achieve a gain of two magnitudes with
respect to its predecessor HARPS, and the instrumental radial-velocity precision will be improved to reach 10 cm/s level.
We have constituted a Consortium of astronomical research institutes to fund, design and build ESPRESSO on behalf of
and in collaboration with ESO, the European Southern Observatory. The project has passed the preliminary design
review in November 2011. The spectrograph will be installed at the so-called "Combined Coudé Laboratory" of the
VLT, it will be linked to the four 8.2 meters Unit Telescopes (UT) through four optical "Coudé trains" and will be
operated either with a single telescope or with up to four UTs. In exchange of the major financial and human effort the
building Consortium will be awarded with guaranteed observing time (GTO), which will be invested in a common
scientific program. Thanks to its characteristics and the ability of combining incoherently the light of 4 large telescopes,
ESPRESSO will offer new possibilities in many fields of astronomy. Our main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of quiet, near-by G to M-dwarfs, and the analysis
of the variability of fundamental physical constants. In this paper, we present the ambitious scientific objectives, the
capabilities of ESPRESSO, the technical solutions for the system and its subsystems, enlightening the main differences
between ESPRESSO and its predecessors. The project aspects of this facility are also described, from the consortium and
partnership structure to the planning phases and milestones.