  A brief overview of the QCD phase diagram at nonzero temperature and density
is provided. It is explained why standard lattice QCD techniques are not
immediately applicable for its determination, due to the sign problem. We then
discuss a selection of recent lattice approaches that attempt to evade the sign
problem and classify them according to the underlying principle: constrained
simulations (density of states, histograms), holomorphicity (complex Langevin,
Lefschetz thimbles), partial summations (clusters, subsets, bags) and change in
integration order (strong coupling, dual formulations).
