Windows 10: Data Hard Drive in This PC

I got this PC yesterday and have noticed that there is a random empty drive in This PC. It says "762 GB free of 763 GB."
Does this come with every OS and what is it used for?

:)

 

How do i move my entire hard drive files to an external hard drive

I'm planning to move my entire hard drive data to an external hard drive but I was wondering where to look in my folders to move my entire hard drive data (including the data across other accounts I have made on this pc) to the external hard drive.

 

Disk partitons

If you have formatted the other partitions, you need to pull the hard drive out of that PC and put it into another PC alongside the existing hard drive and backup your data in that PC . . .

 

There's nothing about the computer to go on, no information about it. As strictly a guess I'd say if it's a new computer it may have an SSD [Solid State Drive] as C: and an HDD [Hard Disk Drive] as D: or a secondary drive. It should not be 'random' but it could be empty. SSDs are traditionally rather lower in capacity than HDDs although they are becoming higher in capacity as time marches on.