Wilson loops are among the most interesting observables one can consider in any gauge theory. They are non-local operators associated to the phase acquired by a charged particle propagating in a gauge field and capture global information about the theory they probe. Among other things, they serve as order parameters for confinement/deconfinement phase transitions and as a way to compute the Bremsstrahlung energy of accelerated particles, knot invariants, scattering amplitudes, and so on.

In this informal and minimally technical seminar, I will try to illustrate the many uses of Wilson loops, especially in the context of supersymmetric gauge theories (where sometimes they can be computed exactly thanks to the so-called “localization") and holographic dualities (where they are associated to dual objects as minimal surfaces, D-branes and more complicated geometries). I will try to focus on the concepts, rather than on giving precise details, to try to make this accessible to all.