  In spite of the advent of extremely large telescopes in the UV/optical/NIR
range, the current generation of 8-10m facilities is likely to remain
competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain
U-Band Efficient Spectrograph (CUBES) has been designed to provide
high-efficiency (>40%) observations in the near UV (305-400 nm requirement,
300-420 nm goal) at a spectral resolving power of R>20,000, although a
lower-resolution, sky-limited mode of R ~ 7,000 is also planned.
  CUBES will offer new possibilities in many fields of astrophysics, providing
access to key lines of stellar spectra: a tremendous diversity of iron-peak and
heavy elements, lighter elements (in particular Beryllium) and light-element
molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump
(particularly important for young stellar objects). The UV range is also
critical in extragalactic studies: the circumgalactic medium of distant
galaxies, the contribution of different types of sources to the cosmic UV
background, the measurement of H2 and primordial Deuterium in a regime of
relatively transparent intergalactic medium, and follow-up of explosive
transients.
  The CUBES project completed a Phase A conceptual design in June 2021 and has
now entered the Phase B dedicated to detailed design and construction. First
science operations are planned for 2028. In this paper, we briefly describe the
CUBES project development and goals, the main science cases, the instrument
design and the project organization and management.
