Nuclear energy is playing a vital role in the life of every man, woman, and child in the United States today. In the years ahead, it will affect increasingly all the people of the Earth. It is essential that all Americans gain an understanding of this vital force if they are to discharge thoughtfully their responsibilities as citizens and if they are to realize fully the myriad benefits that nuclear energy offers them. The United States Atomic Energy Commission provides this booklet to help you achieve such understanding. -- Edward J. Brunenkant, Director, Division of Technical Information