  We present the third data release of the European Space Agency's Gaia
mission, GDR3. The GDR3 catalogue is the outcome of the processing of raw data
collected with the Gaia instruments during the first 34 months of the mission
by the Gaia Data Processing and Analysis Consortium. The GDR3 catalogue
contains the same source list, celestial positions, proper motions, parallaxes,
and broad band photometry in the G, G$_{BP}$, and G$_{RP}$ pass-bands already
present in the Early Third Data Release. GDR3 introduces an impressive wealth
of new data products. More than 33 million objects in the ranges $G_{rvs} < 14$
and $3100 <T_{eff} <14500 $, have new determinations of their mean radial
velocities based on data collected by Gaia. We provide G$_{rvs}$ magnitudes for
most sources with radial velocities, and a line broadening parameter is listed
for a subset of these. Mean Gaia spectra are made available to the community.
The GDR3 catalogue includes about 1 million mean spectra from the radial
velocity spectrometer, and about 220 million low-resolution blue and red prism
photometer BPRP mean spectra. The results of the analysis of epoch photometry
are provided for some 10 million sources across 24 variability types. GDR3
includes astrophysical parameters and source class probabilities for about 470
million and 1500 million sources, respectively, including stars, galaxies, and
quasars. Orbital elements and trend parameters are provided for some $800\,000$
astrometric, spectroscopic and eclipsing binaries. More than $150\,000$ Solar
System objects, including new discoveries, with preliminary orbital solutions
and individual epoch observations are part of this release. Reflectance spectra
derived from the epoch BPRP spectral data are published for about 60\,000
asteroids. Finally, an additional data set is provided, namely the Gaia
Andromeda Photometric Survey (abridged)
