Viral diseases entail great losses to poultry industry as they can reduce flock performance, productivity and profits without appearing as overt clinical diseases. Viruses can cause primary tissue damage and open the gates for other infectious agents (bacteria, mycoplasmas...). Therefore, effective biosecurity measures and vaccination programs are required to maintain a healthy immune status within the flock. This handy and rigorous book is focused on the main viral infections in poultry farming and includes the most updated information as well as numerous graphic resources (high quality images, graphs, flow charts) to better understand the content. The book has been written by an author with a wide experience in the study of these infections and their management and control in the field. Its format makes the contents more understandable and accessible to readers.