  The RHIC program was intended to identify and study the quark-gluon plasma
formed in the collision of heavy nuclei. The discovery of the "perfect liquid"
is an essential step towards the understanding of the medium formed in these
collisions. Much of data relevant to this was provided by the study of "soft"
observables, which involve many particles of low momentum produced in nearly
every event, rather than high momentum particles produced in rare events. The
main results related to soft physics at RHIC are discussed, as well as their
implications for the physics of the LHC heavy ion program.
