Understanding Drupal version numbers

This guide introduces Drupal’s version numbering scheme for Drupal core, contributed modules and themes. The contents of the guide are intended to help you understand what the various version numbers mean, and how you can use that information when building a Drupal site.

The Drupal core version numbering scheme is simple enough: Major.Minor.Patch - for example 8.8.5. The major version number indicates compatibility, the minor version number indicates new significant features and the patch number indicates bug fixes and minor enhancements.

Taking a look at the core release overview is very useful - either before or after reading this guide.