Why?

Thanks to Semantic Versioning, the idea of using version identifiers to communicate intentions to the consumers of artifacts has become widely accepted. It relieved consumers of the “dependency hell” and allowed for an automatic handling of dependencies.

However, some artifact providers felt that SemVer was not flexible enough to express finer-grained levels of backwards-incompatibility, it wasn’t specially suited for more complex releasing cycles, or even that it discouraged rapid development and fast iteration.

Pragmatic Versioning accepts that sometimes relatively frequent backwards-incompatible changes are required as a normal part of the evolution of an artifact, and doesn’t treat these phases as an exception in which versioning conventions should be dismissed. Instead of that, the providers have an additional semantic number available to express not simply backwards-incompatibility but a wider type of potentially conflicting modifications, that can be used to modulate the releases in a more meaningful way.