This channel collects the lectures during the GGI program "Geometry of Strings and Fields" held at GGI from August 26, 2013 to October 18,2013 and organized by Francesco Bonechi (INFN), Alberto Cattaneo (Zurich University), Sergei Gukov (Caltech University), Martin Rocek (Stony Brook University), Domenico Seminara (Università di Firenze) and Maxim Zabzine (Uppsala University)