The Schwarz function originates in classical complex analysis and potential theory. In this text, the author presents the advantages of the function, favouring a mode of treatment which unites the subject with modern theory of distributions and partial differential equations - thus bridging the gap between two-dimensional analysts. The author examines the Schwarz function and its relationship to recent investigations regarding inverse problems of Newtonian gravitation, free boundaries, Hele-Shaw flows and the propagation of singularities for holomorphic partial differential equations.