This book covers all aspects of naturally occurring phenomenon of Plant-Pathogen Interaction (PPI). Recent findings and scientific explanations to understand PPI are provided accompanied by numerous helpful photographs and pictorial presentations. In addition, tabulated data is also included to aid in getting insight into the subject and identifying the missing links. Essential information is provided on physiological, biochemical and pathology consequences of PPI and distinguished sections are devoted to explain molecular and regulatory mechanism underlying PPI. Further topics include different classes of plant pathogen, receptor molecules, signaling system, secondary metabolism and plant defense system etc. This book helps the readers in understanding the state of art and emerging technics to explore PPI and in identifying the missing links which further help in creating the background for future exploration of PPI in terms of experimental and technical advancements.