Lattice QCD: a primer of methods and results

The lattice regularization of Quantum Field Theories is a first-principles approach that allows to explore their non-perturbative regime via computer simulations. Over the years, it has provided valuable inputs to experimental studies and has contributed to the understanding of some of the deepest features of strongly-interacting field theories. The constant improvement of algorithms and computational power makes the lattice regularization an essential tool in the hands of the theoretical physicists of the future. In these lectures, the theoretical foundations of this approach will be reviewed, and some of the main results and currently open problems will be discussed.