Every software we use daily has software version and we should also give version number to software we develop everyday.
The simplest one is Semantic Versioning.(http://semver.org/)
Give software version no in form of MAJOR.MINOR.PATCH
- MAJOR: Increment it on every major release
- MINOR: increment it on every new feature introduction
- PATCH: increment it in every bug fixes or small changes
Here is one example :
- When you start developing any software give it 0.0.1
- when you introduce any new feature/module change number to 0.1.0
- when you add another module change number ot 0.2.0
- When you made some changes/bug fixes change version to 0.2.1
- Once software is ready for publish give it number 1.0.0
Query: When should I change software version number?
Answer: Every time you commit the code you should increment it.(obviously you should use source control systems)
Query: Where can I store it?
Answer: Put it anywhere in project. as Constant in code or version.txt or version.xml or version.json as you like