Discrete Event Physics introduces a new branch of Physics directly concerned with elucidating the meaning of concepts traditionally studied in that discipline. It is complementary to Mathematical and Experimental Physics, being focused on the same ideas but having different specific goals. The theory has a fundamentally dynamic nature, its basic ingredients being structured discrete events, causal relations between events, and event properties. Formal languages are defined for defining events and properties and for comparing definitions, in particular definitions formulated in different paradigms. The theoretical ideas are exemplified by applications to Space and Time. In this context possible answers to many of the most fundamental unresolved problems in Physics are suggested: . the nature of time, its apparent continuity, its apparent flow and directionality . the nature of space, its apparent continuity, and the reasons behind its dimensionality . the nature of matter . the possible utility of numbers in defining meaning