In light of the current era of the ongoing Covid-19 pandemic it is extremely important to have a clear knowledge of the various viruses that jeopardize health and quality of life and their diagnosis based on clinical manifestations. Early diagnosis is the key to combat any potentially life-threatening diseases. This book aims to give a complete overview of the prevalence diagnosis prevention and management of viral diseases. This book also covers the brief anatomy and pathogenesis of a virus along with a clear classification of viral diseases based on causative agents. The pictorial presentation of various viral infections and their oral signs makes this book a perfect guideline to easily understand distinguish and diagnose various viral diseases.