Semantic Versioning (Semver)

Semantic versioning, often abbreviated as SemVer, is a versioning scheme for software that aims to convey meaning about the underlying changes with each new release. It's a widespread practice adopted in many software projects, including React JS.

In Semantic Versioning, a version number is broken down into three parts: MAJOR.MINOR.PATCH.

- MAJOR version: This will increment when there are incompatible changes in the API, suggesting that such updates might break the existing code.
- MINOR version: This increments when new features are added in a backwards-compatible manner. The addition of new features wouldn't break the current functionality of the app.
- PATCH version: This is incremented when backward-compatible bug fixes are made. These are usually small updates that fix bugs in the current version.

Consider React JS version 16.13.1, for example, where '16' denotes the major version, '13' the minor version, and '1' the patch version. When the React team releases an update, based on the changes, one of these numbers will change.

So if they introduce a new feature that won't break the existing projects, the minor version might be bumped to 14, with the new version becoming 16.14.0. But, if they make changes that could potentially break the existing projects, then the major version might increase to 17, and the version would become 17.0.0.

Semantic versioning like this helps developers to easily understand the scope of updates, enabling them to update their projects to a new version of software with a clear understanding of the potential effects on their own code.