Version numbers become important when you have larger installations.
The following list shows the basic principles of version naming:
Version numbers should grow monotonically, that is, become larger
They should be comparable to each other, and it should be easy to see which version is newer
Use the same scheme for all your artifacts
This usually translates to a version number with three or four parts:
The first is major—changes here signal major changes in the code
The second is for minor changes, which are backward API compatible
The third is for bug fixes
The fourth can be a build number
While this might seem simple, it is a sufficiently complex area to have created a standardization effort in the form of SemVer, or Semantic Versioning. The full specification can be read at http://semver.org.
It is convenient that all installable artifacts have a proper release number and a corresponding tag in the source code management system.
Some tools don't work this way. Maven, the Java...