Hard Drive - Hard Disk or HDD is a similar thing, it is a physical circle that we use to store all the littlest records in our PC.

The contrast between hard disk and RAM is that, the hard plate is the thing which comes in the store, yet RAM proves to be useful to run the things put away in that capacity.

When we kill the PC, anything that is found in the RAM gets cleared. Yet, when the PC is off in HDD, the information isn't deleted.

There is a plate pivot inside the hard disk, the quicker the plate is speedier, the information can be put away or read quicker. We measure hard plate turn speed in RPM (Revolutions Per Minute). Most hard circles are 5400 rpm or 7200 rmp, clearly 7200 rmp's hard plate is speedier than 5400 rmp.