Plant-pathogen interactions is a rapidly developing area among the plant sciences. Molecular genetics has provided the tools to analyze and manipulate mechanisms of pathogenicity and resistance responses and has facilitated their study from the population to the molecular level. This study brings together the views of experts in the field and provides an overview of the genetic basis of interactions between fungi, bacteria, viruses and their host plants, the triggering of plant defences and the complex array of plant responses to stop pathogen invasion, as well as possible applications for improved plant protection. The chapters are organized and written to make an advanced textbook rather than simply a collection of reviews or something resembling conference proceedings. Thus, authors have largely concentrated on a didactic approach and the book should remain useable for several years in spite of the rapid progress in research. The text is aimed at advanced students in the field of plant pathology as well as researchers requiring an integrated picture of plant resistance to pathogens.