HDD stands for Hard Disk Drive.

Explanation:
A hard disk drive (HDD) is a type of computer storage device that uses magnetic storage to store and retrieve digital information. It is a non-volatile storage medium, meaning it retains data even when the computer is turned off.

Components of HDD:
1. Platters: HDDs consist of one or more rotating disks called platters. These platters are coated with a magnetic material that allows data to be written and read using a read/write head.
2. Read/Write Head: The read/write head is responsible for reading and writing data to the platters. It moves across the surface of the platters and magnetically changes the orientation of the particles to store and retrieve the data.
3. Actuator Arm: The actuator arm positions the read/write head over the correct location on the platters to access the desired data. It moves the head radially across the platters.
4. Spindle: The spindle is responsible for rotating the platters at a high speed. The platters spin at speeds typically ranging from 5,400 to 15,000 revolutions per minute (RPM).

Functioning of HDD:
1. Writing Data: When data is written to an HDD, the read/write head magnetically changes the orientation of the particles on the platter's surface. This creates a magnetic pattern that represents the data.
2. Reading Data: To read data, the read/write head detects the magnetic field on the platter's surface. It converts the magnetic pattern back into electrical signals that the computer can understand.
3. Accessing Data: The actuator arm positions the read/write head over the correct track on the platter to access the data. The head moves in small increments across the platter to read or write data from multiple locations.

Advantages of HDD:
- High storage capacity: HDDs can store a large amount of data, ranging from several gigabytes to several terabytes.
- Cost-effective: HDDs are relatively inexpensive compared to other storage solutions.
- Widespread compatibility: HDDs are compatible with most computers and operating systems.

In conclusion, HDD stands for Hard Disk Drive, which is a magnetic storage device used for storing and retrieving digital data. It consists of rotating platters, read/write heads, an actuator arm, and a spindle. HDDs are known for their high storage capacity, cost-effectiveness, and compatibility with various systems.

Hard disk drive