  Fluctuations and correlations of conserved quantities (baryon number,
strangeness, and charge) can be used to probe phases of strongly interacting
QCD matter and the possible existence of a critical point in the phase diagram.
The cumulants of the multiplicity distributions related to these conserved
quantities are expected to be sensitive to possible increased fluctuations near
a critical point and ratios of the cumulants can be directly compared to the
ratios of the susceptibilities from Lattice QCD calculations. In these
proceedings, the measurements of the cumulants of net-proton multiplicity
distributions from Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6,
27, 39, 62.4 (up to fourth order) and 200 GeV (up to sixth order) as measured
by the STAR experiment at RHIC will be presented. Multi-particle correlation
functions will also be presented.
  The measurement of higher-order cumulants are sensitive to experimental
artifacts. Current efficiency correction methods are based on the assumption
that the tracking efficiency is strictly binomial. An unfolding technique is
used to account for multiplicity dependent detector responses and efficiency
variations. A large sample of AMPT events will be used to check the validity of
the unfolding technique. The comparison of the various correction approaches
should provide important guidance towards a reliable experimental determination
of the multiplicity cumulants.
