The Hard Drive or Hard Disk is the permanent storage device for your computer. It is were all programs and saved information are stored. The hard drive perhaps the only part of the computer with moving parts. Like a CPU it uses data in the basic form of binary. Programs that you use are loaded initially from the hard drive but not directly to the CPU.     Having moving parts the hard drive is the most volatile piece of equipment in the computer. Dust inside the hard drive could ruin it. That is why it is sealed air tight so nothing can get to it. Another problem with it having moving parts is wear and tear. The hard drive especially on new computers is moving very fast it can rotate any where from 4000 to 10000 RPM. This can wear down the components fast and makes hard drives break down and stop working.