Krita is being developed and improved every day. Even though there are features constantly being added, you might not want every change. New features can create bugs and cause Krita to crash. This could be dangerous if you are counting on the application to be stable.
Applications such as Krita are developed in release cycles. Every version of Krita has a process it follows. This process helps control each new version of Krita so it gets the most features added while trying to make it as stable as possible.
When you look at the splash page when Krita launches, you will see the release type and number under the splash graphic. This will tell you what type of build was done with Krita. A build is when the programmer decides to take all of the code and make a new version of Krita to download.
Spotting what version of Krita you are on: The splash page tells you the version as well as the last code that was added (git number).
Developers do these builds daily when they are adding new features. Sometimes they do a build and share it with everyone on krita.org. Krita uses the following development terminology for each new release.