Function of hard disk

Hi guys will you plz tell me about main function of hard disk drive in computer as I am doing hardware course and it is in my syllabus , so I am collecting its info??

[Kiran Chandar]

As you asked I am telling hard disk drive (HDD), is a data storage device in computer and its main function is storing and retrieving digital information using one or more rigid ("hard") rapidly rotating disks (platters) coated with magnetic material:

In another word hard disk drive used for the impermanent storage of your data files. Also it is where the windows or MAC system files (which make your computer work) are stored.

It is used to store data long term, Its data can be include the computer's operating system and applications as well as personal files including photographs, documents and music.

When a computer is booted up, or turned on, the computer access the hard drive to load the operating system, such as Windows, OSX or Linux.

Improvement of HDD characteristics over time
Parameter Started with Developed to Improvement
Capacity
(formatted) 3.75 megabytes 10 terabytes 2.7-million-to-one
Physical volume 68 cubic feet (1.9 m3)[c] 2.1 cubic inches (34 cc) 56,000-to-one
Weight 2,000 pounds (910 kg) 2.2 ounces (62 g) 15,000-to-one
Average access time about 600 milliseconds a few milliseconds about
200-to-one
Price US$9,200 per megabyte $0.032 per gigabyte by 2015 300-million-to-one
Areal density 2,000 bits per square inch 826 gigabits per square inch in 2014 greater than 400-million-to-one