The article discusses the interaction between paper and electronic documents in two distinct worlds: the physical desk and the electronic workstation. The author, Pierre Wellner, highlights the limitations and advantages of each world and the challenges in integrating them. The "desktop metaphor" is a classic approach to making electronic workstations more familiar and accessible, but it still falls short in fully leveraging the tactile and spatial skills of users. The DigitalDesk is introduced as a novel solution that combines the physical and electronic worlds, allowing users to interact with both paper and electronic documents simultaneously. The DigitalDesk projects electronic images onto the desk, responds to interactions with pens or fingers, and can read paper documents placed on it. The article describes several prototype applications, including a calculator, PaperPaint, and DoubleDigitalDesk, which demonstrate how the DigitalDesk can enhance the functionality of paper documents. The implementation issues, such as interaction on the desk, reading paper documents, and self-calibration, are also discussed. User experiences suggest that the DigitalDesk is comfortable and natural to use, offering more space, better eye comfort, and a more manual interaction style compared to traditional workstations. The article concludes by emphasizing the importance of integrating computers into the physical world rather than the other way around, and acknowledges the contributions of various researchers in the field.The article discusses the interaction between paper and electronic documents in two distinct worlds: the physical desk and the electronic workstation. The author, Pierre Wellner, highlights the limitations and advantages of each world and the challenges in integrating them. The "desktop metaphor" is a classic approach to making electronic workstations more familiar and accessible, but it still falls short in fully leveraging the tactile and spatial skills of users. The DigitalDesk is introduced as a novel solution that combines the physical and electronic worlds, allowing users to interact with both paper and electronic documents simultaneously. The DigitalDesk projects electronic images onto the desk, responds to interactions with pens or fingers, and can read paper documents placed on it. The article describes several prototype applications, including a calculator, PaperPaint, and DoubleDigitalDesk, which demonstrate how the DigitalDesk can enhance the functionality of paper documents. The implementation issues, such as interaction on the desk, reading paper documents, and self-calibration, are also discussed. User experiences suggest that the DigitalDesk is comfortable and natural to use, offering more space, better eye comfort, and a more manual interaction style compared to traditional workstations. The article concludes by emphasizing the importance of integrating computers into the physical world rather than the other way around, and acknowledges the contributions of various researchers in the field.