The document discusses surface computing and the Microsoft Surface tabletop computer. It provides background on surface computing, how the Surface works using infrared cameras and rear projection, and examples of how the Surface is used. It also summarizes a study where participants defined over 1000 gestures for interacting with the Surface and taxonomy of surface gestures. Key challenges of the Surface include cost and lack of portability. The document concludes the user study helps develop gestures for tabletop systems and Surface changes how people interact with technology.