# Variation > **Machine-Evolution Nexus:** [[articles/Digital Darwinism and the Invisible World of Machine Evolution|Digital Darwinism and the Invisible World of Machine Evolution]] provides the evolutionary and computational context for this supporting concept. **Domain:** Evolution / Difference **Doc Type:** Supporting Canonical Node **Maturity:** Developed ## Definition Variation is difference among entities, states or descendants. ## Nexus Context Only heritable variation affecting differential persistence enters Darwinian evolution. This distinction prevents every software change or behavioral fluctuation from being called a mutation. ## Relationships [[wiki/Heritable Variation|Heritable Variation]], [[wiki/Mutation|Mutation]], [[wiki/Genetic Recombination|Genetic Recombination]], [[wiki/Darwinian Evolution|Darwinian Evolution]] ## Sources / Provenance - Developed from the cited research in the central article and the surrounding continuity, rights and evolutionary architecture.