  We review the equation of state of QCD matter at finite densities. We discuss
the construction of the equation of state with net baryon number, electric
charge, and strangeness using the results of lattice QCD simulations and hadron
resonance gas models. Its application to the hydrodynamic analyses of
relativistic nuclear collisions suggests that the interplay of multiple
conserved charges is important in the quantitative understanding of the dense
nuclear matter created at lower beam energies. Several different models of the
QCD equation of state are discussed for comparison.
