This volume contains three contributions in the field of logic and computation that reflect current trends towards an interactive account of the meaning of proofs and programs. The contributions can be read independently and use or introduce fundamental tools in the field: categories, realizability, abstract machines. Throughout the volume, a unifying theme is that of games and strategies, which turns the correspondence between proofs and programs (the so-called Curry-Howard isomorphism) into a triangle whose third corner emphasizes interaction and duality between a program and its environment or between a proof and counter-proofs. The introduction to the volume places the contributions in perspective and provides a gentle beginner's introduction to the lambda-calculus, which is and remains the backbone of the whole field.