Sexually Transmitted Diseases (STDs) are among the most common infectious diseases in the United States today. More than 20 STDs have been identified, and they affect more than 13 million men and women in the United States each year. Nearly two-thirds of all STDs occur in people younger than 25 years of age. Understanding the basic facts about STDs--how they are spread, their symptoms, and how they are treated--is the first step toward prevention. The new edition of Sexually Transmitted Diseases Sourcebook provides updated information about the symptoms, diagnosis, and treatment of most sexually transmitted diseases. It also covers prevention issues, such as condom use, vaccines, and STD education, and issues related to youth and adolescents. A glossary and a list of resources for additional help and information are also included.