  We review the recent theoretical and experimental progress regarding the
Generalized Hydrodynamics (GHD) behavior of the one-dimensional Bose gas with
contact repulsive interactions, also known as the Lieb-Liniger gas. In the
first section, we review the theory of the Lieb-Liniger gas, introducing the
key notions of the rapidities and of the rapidity distribution. The latter
characterizes the Lieb-Liniger gas after relaxation and is at the heart of GHD.
We also present the asymptotic regimes of the Lieb-Liniger gas with their
dedicated approximate descriptions. In the second section we enter the core of
the subject and review the theoretical results on GHD in 1D Bose gases. The
third and fourth sections are dedicated to experimental results obtained in
cold atoms experiments: the experimental realization of the Lieb-Liniger model
is presented in section 3, with a selection of key results for systems at
equilibrium, and section 4 presents the experimental tests of the GHD theory.
In section 5 we review the effects of atom losses, which, assuming slow loss
processes, can be described within the GHD framework. We conclude with a few
open questions.
