The science fiction concept of nanotechnology is here and in use today! Micro Machines much smaller than the width of a single human hair are already being used in wrinkle-free clothing, skin moisturizers, and automobile air bag sensors. The medical profession is studying ways to use nanoparticles to deliver medications inside the body over periods of several weeks to fight cancer inside blood vessels The potential uses of this tiny technology are truly mind-boggling. All of the information from an entire set of encyclopedias could be placed on the head of a pin. This tiny particle could then be implanted into the brain to produce a very smart person. Robots smaller than insects are being developed to study aspects of the environment and to explore places, such as caves and deep valleys. Experiments have been tightly controlled, but some people have expressed concern that nonobots could escape their scientific laboratories. No one knows what would happen if they came in contact with plant and animal life. What if they start reproducing on their own? Large, full-color photographs, drawings, and diagrams aid the reader in comprehending the miniscule size of these mini-machines and some of their uses. A time line, a glossary, and an index are included. A part of the "Science Frontiers" series.