Snapshots are used to capture a VM's current state, and allow you to seamlessly revert back to that state if needed.
Snapshots can be created in two different ways:

You will then be prompted to name your snapshot, and add a description for it. Both of these fields are optional, and can be left blank
To view and manage existing snapshots, navigate to the VM's Configuration ⇒ Snapshots tab

Here, you can view what snapshots exist on the VM, their tree structure, and which snapshot the host is currently active on.
By clicking a snapshot, you can view its details, and options to Delete or Revert to the snapshot.
