Elefant saves a version history of most types of content on your site, including pages, blocks, and blog posts.
To access the version history for a given page or block, click on the Versions button in the edit button list for that item. This will bring up a list of all the saved versions for that item.
From here, you can compare any previous version to the current version, and Elefant will highlight the fields that have been changed in a side-by-side view. You can restore a previous version from the comparison screen.
You can also access the version history for the whole site under Tools > Versions.