computer's main "long term memory" and "data center"- This is where your files are permanently stored on your computer. Also, normally, your operating system is installed here.

Hard drives are the fastest form of long-term storage your computer uses and the device stay in one place inside the computer and cannot be removed the way floppy disks or CD-ROMs can.

Hard disk plays a significant role in the following important aspects of the  computer system:

• Performance: The speed at which the PC boots up and programs load is directly related to hard disk speed. The hard disk's performance is also critical when multitasking is being used or when processing large amounts of data such as graphics work, editing sound and video, or working with databases.

   

• Storage Capacity: A bigger hard disk lets you store more programs and data.

   

• Software Support: Newer software needs more space and faster hard disks to load it efficiently. Now a PC with even 10 GB is considered by many to be "crippled", since it can barely hold modern (inflated) operating system files and a complement of standard business software.