Algebraic Geometry and Discrete Periodic Operators Spectral theory of operators on a periodic medium is a topic in mathematical physics having deep interactions with analysis. Its discretization, operators on periodic graphs, additionally communicates with discrete mathematics and algebraic geometry. Many natural aspects of discrete periodic operators are directly understood in terms of algebraic geometry and some basic questions are answered using standard techniques from algebraic geometry. My talk will explain some algebraic aspects of discrete periodic operators, illustrating how the interactions flow in both directions, to the benefit of both disciplines.