Abstract: A virtual synchronization methodology enables on-demand data delivery so that revisions are downloaded “just-in-time” to a client machine upon an observer's access of the files rather than downloading all the revisions upfront using the static and monolithic methodology in a conventional synchronization. When virtual synchronization is invoked, a preview of the changes in the file state that have occurred since the last synchronization is obtained and used to generate virtualized files with which the observer can interact and see the changes as if the files were actually synchronized. A virtualized file is then populated with actual data on-demand when accessed by the observer or by a system or process that is operating on the client machine.