Version History
SharePoint supports version history for both Lists and Libraries.
Lists can be configured to allow you to keep a numbered version for each edit you make. So, version 1, 2, 3 etc.
In addition to this, Libraries support both major and minor versions – most commonly used with publishing scenarios.
So, version 0.1, 0.2 etc are drafts.
Check in and publish, and it becomes version 1.0.
More edits make version 1.1, 1.2 until you next publish and it becomes version 2.0, and so on.
For Lists and Libraries you create, SharePoint on-premise defaults to no version history.
SharePoint Online has a different default for Libraries: it keeps the last 500 major versions.
When figuring out how much of your storage quota you’ve used, bear in mind that any kept versions will take up storage space.
Every time you save a new version of a document, SharePoint cleverly keeps only the delta between the current version and the previous one. This saves an enormous amount of space for heavy users of versioned Libraries.