Add to ORKGIn these lecture notes we present a few basic approaches to the definition of the semantics of programming languages. In particular, we present: (i) the operational semantics and the axiomatic semantics for a simple imperative language, and (ii) the operational semantics and the denotational semantics for some first order and higher order, typed functional languages. We then present some basic techniques for proving properties of imperative, functional, and concurrent programs. We closely follow the presentation done in the book by Glynn Winskel [Win93]. I express my gratitude to my colleagues at the Department of Informatics, Systems, and Production of the University of Roma Tor Vergata, and to my students and my co-workers Fabio Fiorav...