A von Neumann machine is a model for a computing machine that uses a single storage structure to hold both the set of instructions on how to perform the computation and the data required or generated by the computation. John von Neumann helped to create the model as an example of a general-purpose computing machine. By treating the instructions in the same way as the data, the machine could easily change the instructions. In other words the machine was reprogrammable.

In another sense, a von Neumann machine is also a self-replicating machine. In principle, if a machine (for example an industrial robot) could be given enough capability, raw material, and instructions then that robot could make an exact physical copy of itself. The copy would need to be programmed in order to do anything. If both robots were reprogrammable, then the original robot could be instructed to copy its program to the new robot. Both robots would now have the capability of building copies of themselves. Since such a machine is capable of reproduction, it could arguably qualify as a simple form of life. An early fictional treatment was the short story "Autofac" by Philip K. Dick, published in 1955, which precedes von Neumann's original paper about self-reproducing machines (von Neumann, J., 1966, The Theory of Self-reproducing Automata, A. Burks, ed., Univ. of Illinois Press, Urbana, IL).