Autosave
As you make changes to content in the application, most content types will temporarily save the content in the background, so that it can be recovered if you lose your network connection before you get chance to save.
A message will be shown at the top of the page informing you of the last time content was autosaved.
As soon as you save your changes, the application will clear any autosaves it has created for that piece of content, so you can't accidentally overwrite your page with work in progress at a later date.
If there is an autosave available for a page, a message is shown at the top of the page that includes when that autosave was created.
Changes can be recovered, in which case they will overwrite the current content, or dismissed.
Remember to save your changes after recovering the autosaved content.