Where it is: The hard drive is located in an airtight compartment, because if any dust particles happen to touch it, then the needle inscribing the data picks the dust up and scratches the surfac of the disk, ruining the magnetic current, and leading to disk failure.
Where it comes from: The hard disk drive has a short history. about two decades ago it was a huge machine about the size of a small regrigerator. Inside were fifty disks with a two foot diameter, each holdong five megabytes of information. At first disk drives were called drums which were magnetic storage units. Magnetic drums could store a huge amount of data and retrieve data very quickly. Over the years the disk drive went through a few stages of improvement, finally reaching the advanced state that they are in today.