Collaboration in a shared workspace can mean that a document is edited and revised multiple times by different authors. Without version control, the authors would have to do a lot of additional administrative routine work to keep the different versions of the documents apart in their chronological and content-related sequence. Because it is safer and also much more convenient, the authoring group should put their BSCW documents under version control.
When a document is under version control, its contents are not simply overwritten when changes are made; rather, an additional version is created that now represents the current version. The previous versions are preserved. Their sequence is indicated by version numbers (e.g. 0.1, 0.2, 0.3, etc.). You can still access them via the info page or directly via a URL with version number (see below).
As the manager of a folder, you also have the option to place all documents in the folder under automatic version control, so that when new documents are uploaded and existing documents are replaced or edited, documents are automatically created under version control.