Versioning is a key part of content management. The documents that you work with in your business can go through many changes during their lifetime, and versioning information is provided to help manage your document content. The versions of a document provide a history of the changes the document has undergone from the time it was initially created. Document versions are created when you check a document in and out. A version is a document belonging to the Document class or one of the document subclasses. It represents the document as it existed at a particular time in its history, and is individually saved and maintained in an object store. When taken together, the different versions of a document become the version series for the document.
Some changes are not captured in a version:
An icon next to a document indicates if the document is checked in or out, and indicates the version state of the checked out document. The major version number for the document is also displayed (unless removed by your site administrator). When you check out a document, you always check out the current version. The current version of a document is the most recent version in the version series. You can open and view other versions of the document from the document's Information or Properties page. You can promote, demote, or delete document versions.