The meaning of version numbers can vary across projects.

One common scheme is Semantic Versioning, which divides the version number into three parts: MAJOR.MINOR.PATCH*

• MAJOR is incremented when there are backwards incompatible changes.
• MINOR is incremented when new features are added in a backwards compatible way.
• PATCH is incremented for smaller big fixes.
• Each number is reset to zero when a higher level number is incremented.

* It’s a bit more complex than this, but this is the gist.