Tangible User Interfaces
In tangible user interfaces (TUI) a person interacts with digital information through objects in the physical environment. These objects allow the person to grasp and manipulate the objects and therefore the digital representation with their hands.
Hiroshi Ishii, a professor in the MIT Media Laboratory who heads the Tangible Media Group, described and demonstrated his vision of Tangible Bits in [1, 2]. In this work, he gives a physical form to the digital information to "to bridge the gaps between both cyberspace and the physical environment, as well as the foreground and background of human activities". Therefore digital information becomes directly manipulable and perceptible. Metadesk is one example of TUI showing its capabilities while using an interactive map on a desk [3, 4].
 Hiroshi Ishii and Brygg Ullmer. 1997. Tangible bits: towards seamless interfaces between people, bits and atoms. In Proceedings of the ACM SIGCHI Conference on Human factors in computing systems (CHI '97). ACM, New York, NY, USA, 234-241. DOI=10.1145/258549.258715 http://doi.acm.org/10.1145/258549.258715
 Hiroshi Ishii. 2008. Tangible bits: beyond pixels. In Proceedings of the 2nd international conference on Tangible and embedded interaction (TEI '08). ACM, New York, NY, USA, xv-xxv. DOI=10.1145/1347390.1347392 http://doi.acm.org/10.1145/1347390.1347392
 Brygg Ullmer and Hiroshi Ishii. 1997. The metaDESK: models and prototypes for tangible user interfaces. In Proceedings of the 10th annual ACM symposium on User interface software and technology (UIST '97). ACM, New York, NY, USA, 223-232. DOI=10.1145/263407.263551 http://doi.acm.org/10.1145/263407.263551