The Lego Mindstorms Robotics Invention System is clearly a new kind of toy. Introduced in the Fall of 1998, Lego Mindstorms quickly became Lego's best-selling kit of all time. But the market data proved to be the real surprise. From its surveys Lego found that the median purchasing age for the Mindstorms kit is 23. Lego's Mindstorms kit enables anyone to build a programmable robot with an assortment of Lego pieces that snap, slide and clink into place. The Mindstorms Programmable Brick, called the RCX, contains a microcomputer that enables those who build robots to then program their movement. Sensors and motors can be attached to the RCX and suddenly what was an ordinary Lego model comes to life. Not only does it move, but it can also sense and respond to its environment. Given this toy's capabilities, it's not surprising that a whole generation of adults interested in robotics or programming is rediscovering Lego through Mindstorms. The Mindstorms kit does include basic instructions and samples robots, but these are not comprehensive and do not adequately teach the principals of robotics. Without direction, inventing a robot from the ground-up can be quite challenging. Baum's book includes a wide variety of new robots, in-depth explanations for readers, and important theory behind the practice of building robots. In short, the book provides all the information necessary to become a robotics expert with Mindstorms.