In The Nature of Technology, W. Brian Arthur makes the case that all technology has three elements. The first is that there must be some physical phenomenon at its root. Money, for example, is not a technology The second characteristic of technologies is that they are combined and assembled out of other technologies. The third characteristic is, to my mind, the most interesting and subtle:
technologies are recursive. If you look closely at any given technological artifact or process, you can observe that it’s created out of other technologies, and the same is true if you look more carefully at that technology, all the way down to some basic physical phenomenon.
Technologies are either a harness on a basic phenomenon or recursively assembled out of other technologies.