  The outline of the two lectures given in "Dense Matter School 2015" is
presented. After an overview on the relevance of the phase diagram to heavy-ion
collisions and compact star phenomena, I show some basic formulae to discuss
the QCD phase diagram in the mean field treatment of the Nambu-Jona-Lasinio
model. Next, I introduce the strong-coupling lattice QCD, which is one of the
promising methods to access the QCD phase diagram including the first order
phase boundary. In the last part, I discuss the QCD phase diagram in asymmetric
matter, which should be formed in compact star phenomena.
