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== What is a Hyper-V Virtual Machine Snapshot? ==
Hyper-V virtual machine snapshots allow the status of a virtual machine (and the corresponding guest operating system) at a particular time to be saved such that it can be reverted to that state at any point in the future. Hyper-V snapshots contain both the configuration settings of the virtual machine, and the state of the guest operating system at the point the snapshot is taken. Snapshots may be taken of virtual machines when they are running, stopped or saved. It is not possible, however, to take a snapshot of a paused Hyper-V virtual machine.
When a snapshot is taken of a saved or running virtual machine, the snapshot contains the status of both the file system and the memory used by the guest operating system. As such, when the virtual machine is reverted to the snapshot everything, including applications running at the time the snapshot was taken, will be restored to the snapshot status.
If the selected virtual machine is currently running, as is the case in the above illustration, an additional tree entry in the form a a green arrow and the word ''Now'' represents the currently running virtual machine. Right clicking on this tree item provides options to connect to, or access the settings of the virtual machine.
As each snapshot in a tree is selected, the panel beneath the tree panel will update to display additional information about the snapshot together with a thumbnail screenshot of the virtual machine's console at the point the snapshot was initiated. The following figure shows a typical detail panel for a snapshot:
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<td>'''Apply'''</td>
<td>Applies the snapshot to the virtual machine from which it was taken. The virtual machine will revert to the exact state it was in when the snapshot was taken. Any changes made to the virtual machine since the snapshot was taken will be lost. Hyper-V will provide the option to take a new snapshot of the virtual machine's current state before applying the old snapshot.</td>
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* '''Configuration file''' - An XML file containing the current configuration settings of the virtual machine.
* '''Saved state file''' - A ''.vsv'' file containing vietual virtual machine state information.
* '''Differencing disk image file''' - A ''.avhd'' differencing disk.
* '''Memory image file''' - A ''.bin'' file containing an image of the virtual machine's memory at the point the snapshot was taken.
