Page History
...
Schema snapshots allow you to maintain a history of schema changes. You can take schema snapshots at different points in time and then you can compare those snapshots to each other or compare the snapshots to the live database to get a clear an accurate picture of the "evolution" of the database schema.
Take a snapshot
To take a schema snapshot, simply move the mouse over the name of the database on the left panel of the Workspace and you will see a "camera" icon appear on the side of the database name. Click on that icon to take the snapshot - you will be asked to choose the name of the snapshot and the location where you wish to save it.
Adding snapshots to the workspace
Before comparing snapshots to each other or to live databases you will need to add the snapshots you need to the workspace. The Add Snapshots functionality can be accessed from the ribbon (the Home tab).
...