Design strategies and technology of Elettra 2.0 for a versatile offer to the user community

Elettra 2.0 will be a fourth generation storage ring light source replacing the existing Elettra synchrotron. This article illustrates design strategies, physical in-vestigations and technical choices to meet multiple and sometimes conflicting requirements. These include to make Elettra 2.0 a fully transversely coherent source up to 0.5 keV-photon energy, diversify the type of experiments through a very broad range of photon energies, from infrared to hard x-rays, maximize the number of photon beamlines in excess of 2-times the machine periodicity, and be able to produce picosecond-long light pulses at MHz repetition rate without interference to the standard multi-bunch operation. Most recent advancements in beam physics, technical systems and installation plan are reported with some detail.