You can use versioning without actually using any workflow steps. In other words, it is possible to have a new document version created whenever a document is modified and saved.
Enabling content versioningTo enable versioning without workflow, you only need to enable the Automatically publish changes option either when creating a new workflow, or when editing a workflow on its General tab in the Workflows application. With this option enabled, custom steps can't be created on the Steps tab. You only need to define appropriate scope(s) so that the workflow affects the required documents.
From the end-user point of view, editing a document using versioning without workflow is the same as if the document was using no workflow at all. The Submit to approval, Approve and Reject buttons are not displayed on the document editing form - only the standard Save button is available.
On the Properties -> Workflow tab of a particular document, you can recognize a document using versioning without workflow by the "Any change to the document is automatically published." sentence. You may also notice that the document remains in the Published step all the time until it gets archived.