A computer hard drive is where computer data is stored. An HDD or Had disk drive, is generally referred to as the secondary computer storage device, and the RAM (Random Access Memory) is the primary. Stored data on the RAM is volatile, meaning when the computer is shut down then the information will be lost.
Understand Hard Drives
When the computer is turned on, the Boot process begins, which tells the computer to go to the hard drive for the Operating System.
A hard drive is a permanent storage device. Even when the computer is turned off the information remains stored in there. The operating system, program files, and all data files are stored on the hard drive. A computer can work without a hard drive but in that case there would be no operating systems or programs so it would not be very useful.
Circular platters store data on a hard drive. If you open a hard drive case, the platters get contaminated by air and it is unlikely that it would work again. The actuator arm runs between the platters reading the information in 1’s and 0’s. The arm’s head reads data even when the disk is running at 7200 rpms (a common hard drive speed). This only means that the platter is doing 7200 rounds per minute. Computer hard drives can now do up to 15,000 rpms. As the platters go round and round the head reads it and processes the information which then proceeds to the connector which connects to the computer.
External or Internal?
Hard drives that are inside a computer are called internal hard drives. External hard drives, connect to the computer through USB or Firewire.
External drives are useful for backing up your computer and for transferring files to two locations. These drives are also portable.
Hard Drive Capacity
A Hard drive is measured in Gigabytes. For example, a computer may have a 60Gb (Gigabyte) hard drive. Different files take up different amounts of space. Video files and pictures take up a lot of space, but simple text files take barely anything. The operating system and program files take up space as well. Hard drive capacities vary between 1Gb (or less) to 2Tb (maybe even bigger).