What snapshot and patching at a server mean ?

Suppose you want to test a new software before deploying it in your production servers. You prepared a new physical server or virtual machine for this test. You installed an OS, applied patches, ...etc. The OS now is in original state. From that point, you grabbed your camera and took a shot (or Snapshot) at that OS state. Now, you installed your new software and it doesn't function propely. You can quicly use the shot that you took to revert back into its original state. Another pretty benefit is you can even clone from a snapshot.

Please vote if it helps.

For VIRTUAL server

If you are familiar with Change Control Management best practices a change control say to patch a server with latest kernel/security pathes from OEM support to have your system upto date you MUST need to have backout procedure to restore system to previous state else it will not be approved by Change Management Officer /Manager which is MOST important even Implementation Plan .SNAPSHOT will be best backout procedure when you want to patch your virtual server which allows you to restore your virtual server to previous state if your patching/upgrade went wrong ( I mean if you are not able to boot your virtual server after patching or patching has adversally impacted your server in terms of performance or my any means impacted.

Basically SNAPSHOT is system image at point of time which is used to restore system status of that time.Thus if you look in Virtual Center Console you can see the comment "You are here".

For PHYSICAL servers for instance if you ave used veritas for mirroring OS and you need to broke the mirror before you start applying patch on live disk if every thing goes correct you can simply attach the mirror and allow it to sync with latest updated drive else you can recover system in case of issue after patching by booting from mirror disk.So it gives you system what you have earlier before started applying patch.

For Desktop/Laptop

Same methodology is beeing used since long  in desktop operating systems for instance windows environment callled system recovery.If you are taking system backup .Support you have taken backup one week before and you might have installed some software/spyware from net which has adversally impacted your desktop/laptop then you can restore your system with availablle restore available.

Precisely

1.Only for VIRTUAL Servers.

2.YES used for Backup/Restore.

3.Browse the datastore where your VM exists you can find file.For more details refer to VMWare knowledge base . 

Well, there are couple of snapshots types on a server. They are: Storage snapshot, Virtualization snapshot, Database Snapshot etc. In general snapshot is the state of a system at a particular point in time. It imitates the way a device or file looked at the precise time. It is not the copy of the data itself, only kind of a picture in time how the data was organized.

Patching is defined as "Correction applied to an application/operation system". They are often referred as "fixes" too. A patch is usually developed and distributed as a replacement for or an insertion in compiled code. In operating systems, a special program is provided to manage and keep track of the installation of patches.

well snapshot is when you have  installed runing virtual machine and you want same replica machine so you  create image of the virtual machine with same features , but patching is when you install snap shoted virtual machine and you want to installl new updates on your snapshot that is called patching. or when you upgrading or updating virtual machine updates.

Yes, Yes....

Snapshot word mostly used in Virtual environment, it creates a complete replica / copy of the particular virtual machine at the time when it was created, if you make any changes in that particular VM after taking snapshot then you have the option to revert back to that VM to last snapshot taken if any issue occurs after making any changes.

But patching is different thing, patching keeps your server (OS) or application softwares upto date as most of the Software companies release their patches every month like Microsoft including security patches. So patching help us to keep our system OS & servers away from vulnerability. Patches are the small executables released from application vendors to keep their software / application updated.

Snapshots are real life savers in case of Disaster.

When you take a snapshot, you capture the state of the virtual machine settings and the virtual disk. If you are taking a memory snapshot, you also capture the memory state of the virtual machine. These states are saved to files that reside with the virtual machine's base files.