The United States Society on Dams (USSD) is a professional organization that promotes the advancement of dam engineering and technology, and fosters public awareness of the importance of dams. The best feature on the society's home page is its excellent introduction to dams and their benefits. First, a short definition of a dam is given, and then some reasons for their construction are outlined with specific examples. There are many pictures of dams across the country, and most have explanations for their importance. Hydroelectric power as a renewable resource is discussed in detail. This Web site is a good learning resource for both kids and adults.