  QCD matter at finite temperature and density is a subject that has witnessed
very impressive theoretical developments in the recent years. In this review I
will discuss some new insights on the microscopic degrees of freedom of the QCD
medium near the chiral crossover transition from lattice QCD. Latest high
precision lattice data on the fluctuations and correlations between conserved
charges like the baryon number, strangeness can help us to understand and
distinguish between different models of interacting hadrons. Furthermore, the
latest constraints on the location of the critical end-point and the curvature
of the critical line will be discussed. In the later part of this review I will
discuss about the insights on the thermal nature of the medium created in heavy
ion collision experiments that have come from the theoretical analysis of the
particle yields, and to what extent the lattice data on correlations and
fluctuations of conserved charges can give us any information about the
fireball at freezeout.
