This book written by international authorities in the field consists of 14 chapters, summarizing the most recent progress in the major plant virus research areas, pointing out current challenges and discussing future prospects. This book is an ideal reference book for teachers, senior undergraduate students, graduate students, and scientists who are interested in plant biology, microbiology, pathology and virology. Since the discovery of the first virus tobacco mosaic virus in 1890s, virology has become a subject of science. As an obligate intracellular parasite, virus virtually infects all living organisms and exclusively lives and multiplies in its host cells. Viral infections cause significant losses. In plants, virus infections often reduce crop yields drastically and deteriorate crop quality. As a major branch of virology, plant virology studies plant viruses, aimed at the development of novel antiviral strategies and beneficial uses of viruses. Its core is constituted of the viral life cycle, virus-host biology, viral pathogenesis, immunity to viruses, virus structure, and virus evolution and ecology. Since 1980s, numerous milestone findings in plant virology, such as transcriptional promoters (i.e., the cauliflower mosaic virus 35S promoter), terminations, translational enhancers, and virus-induced gene silencing and suppression of gene silencing, and viral cell-to-cell movement and systemic spread, has contributed enormously to the advancement and development of modern biology and plant biotechnology. More recently, various breakthroughs have led to the rapid advance of this subject. .