  The ESO public survey VISTA Variables in the V\'ia L\'actea (VVV) surveyed
the inner Galactic bulge and the adjacent southern Galactic disk from
$2009-2015$. Upon its conclusion, the complementary VVV eXtended (VVVX) survey
has expanded both the temporal as well as spatial coverage of the original VVV
area, widening it from $562$ to $1700$ sq. deg., as well as providing
additional epochs in $JHK_{\rm s}$ filters from $2016-2023$. With the
completion of VVVX observations during the first semester of 2023, we present
here the observing strategy, a description of data quality and access, and the
legacy of VVVX. VVVX took $\sim 2000$ hours, covering about 4% of the sky in
the bulge and southern disk. VVVX covered most of the gaps left between the VVV
and the VISTA Hemisphere Survey (VHS) areas and extended the VVV time baseline
in the obscured regions affected by high extinction and hence hidden from
optical observations. VVVX provides a deep $JHK_{\rm s}$ catalogue of $\gtrsim
1.5\times10^9$ point sources, as well as a $K_{\rm s}$ band catalogue of $\sim
10^7$ variable sources. Within the existing VVV area, we produced a $5D$ map of
the surveyed region by combining positions, distances, and proper motions of
well-understood distance indicators such as red clump stars, RR Lyrae, and
Cepheid variables. In March 2023 we successfully finished the VVVX survey
observations that started in 2016, an accomplishment for ESO Paranal
Observatory upon 4200 hours of observations for VVV+VVVX. The VVV+VVVX
catalogues complement those from the Gaia mission at low Galactic latitudes and
provide spectroscopic targets for the forthcoming ESO high-multiplex
spectrographs MOONS and 4MOST.
