Self-replicating systems

Self-replicating systems are typically robotic or nanorobotic and reproduce by creating miniature copies of themselves which then grow larger over time. They may have rudimentary or more advanced artificial intelligence code to prevent self-destruction or shutdown from external sources. Systems like these can take over a planet, solar system or beyond, and this uncontrollable spread or swarm can lead to a technological singularity.

Variation:
A nanoswarm capable of spreading and growing, particularly if it has escaped its original parameters and lost control, is commonly referred to as goo. This can be composed of units in many orders of magnitude larger than nanobots. They tend to 'eat' all available material and can become a nuisance or hazard, and in worst cases an uncontrollable infestation that leads to a singularity.