Lattice gauge theory is a well-established non-perturbative approach for solving strongly coupled field theories. Quantum Chromodynamics (QCD), the theory of strong interactions that are responsible for binding quarks into protons and neutrons, and protons and neutrons into nuclei, is an example of a strongly coupled theory where lattice techniques are being successfully applied. At high enough temperatures and/or densities QCD features a new phase of matter, the quark-gluon plasma (QGP), which is being explored in heavy-ion collision experiments at RHIC, BNL and LHC, CERN. In this talk I discuss a recent calculation of the QCD equation of state in the continuum limit and at the physical values of light quark masses, and also certain signatures of deconfinement that are being explored with lattice QCD.