Partial differential equations (pde’s) are for multivariate functions what ordinary differential equations are for functions of a single variable, viz. mutual relations between derivatives of a function. They are encountered in all areas in which modelling of physical systems is central. As such they constitute an important and generically applicable instrument in the physical and applied sciences. Pde’s are typically accompanied by side conditions for disambiguation of their solution, with model dependent coefficients and source terms depending on the system they intend to describe. In this course we focus on linear pde’s and on a number of relevant mathematical techniques used in practice to handle these. Knowledge of linear pde’s is a prerequisite for the study of nonlinear pde’s, and for perturbative and numerical solution methods.