External hard drives, flash drives and other similar forms of removable storage have made life pretty easy when it comes to moving data around. However, we live in a world where each person is likely to own multiple devices that external storage could (theoretically) be connected to.
S. Ghemawat, H. Gobioff, и S. Leung. Proceedings of the nineteenth ACM symposium on Operating systems principles, стр. 29--43. New York, NY, USA, ACM, (2003)