There are some cases when the browser or the machine itself dies while adding/editing some content and we loose the content and we have left with no option but to rewrite/reedit that content.
But now we have a module called Autosave that automatically saves a snapshot of your content. If the user's browser or machine dies while editing a node; the edits will be presented to the user the next time they return to the node. The user may toggle back and forth between the last saved version and the version with the edits that were lost and select which of these they would like to continue with.