  Gaia DR3 publishes a catalogue of full-sky RR Lyrae stars (RRLs) observed
during the initial 34 months of science operations, that were processed through
the Specific Object Study (SOS) pipeline for Cepheids and RRLs (SOS Cep&RRL)
observed by Gaia. The SOS Cep&RRL validation of DR3 candidate RRLs relies on
tools that include the Period (P) G-amplitude diagram and the P-phi21 and
-phi31 parameters of the G light curve Fourier decomposition, based on a sample
of bona fide known RRLs (Gold Sample). The SOS processing led to a catalogue of
271779 RRLs listed in the vari_rrlyrae table of DR3. By dropping sources that
clearly are contaminants, or have an uncertain classification we produce the
final catalogue of SOS-confirmed DR3 RRLs containing 270905 sources (174947
fundamental mode, 93952 first overtone and 2006 double-mode RRLs) confirmed and
fully characterised by the SOS Cep&RRL pipeline. They are distributed all over
the sky, including 95 globular clusters and 25 Milky Way companions. RVS time
series radial velocities are also published for 1096 RRLs and 799 Cepheids. Of
the 270905 DR3 RRLs, 200294 are already known in the literature and 70611 are,
to the best of our knowledge, new discoveries by Gaia. An estimate of the
interstellar absorption is published for 142660 fundamental-mode RRLs from a
relation based on the G-band amplitude and the pulsation period. Metallicities
derived from the Periods and the phi31 Fourier parameters of the G-light curves
are also released for 133559 RRLs. The final Gaia DR3 catalogue of confirmed
RRLs almost doubles the DR2 RRLs catalogue. An increase of statistical
significance, a better characterization of the RRLs pulsational and
astrophysical parameters, and the improved astrometry published with Gaia EDR3,
make the SOS Cep&RRL DR3 sample, the largest, most homogeneous and
parameter-rich catalogue of All-Sky RRLs published so far.
