Semantic Versioning (SemVer) is a versioning scheme that encodes compatibility information in a three-part MAJOR.MINOR.PATCH number: major increments signal breaking changes, minor increments add backward-compatible functionality, and patch increments fix bugs without changing the interface. It gives consumers of a package or API a predictable way to reason about upgrade risk. It is widely adopted across package registries, REST and gRPC API contracts, and machine learning model registries.