The last twenty-five years have seen an increasing interest for variational convergences and for their applications to different fields, like homogenization theory, phase transitions, singular perturbations, boundary value problems in wildly perturbed domains, approximation of variational problems, and non-smooth analysis. Among variational convergences, De Giorgi's Gamma-convergence plays a central role for its compactness properties and for the large number of results concerning Gamma-limits of integral functionals. Moreover, almost all other variational convergences can be easily expressed in the language of Gamma-convergence. This text originates from the notes of the courses on Gamma-convergence held by the author in Trieste and in Rome and is far from being a treatise on Gamma-convergence and its applications.