A hard disk drive (often shortened as "hard disk" or "hard drive"), is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Strictly speaking, "drive" refers to a device distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its floppy disk. Early HDDs had removable media; however, an HDD today is typically a sealed unit (except for a filtered vent hole to equalize air pressure) with fixed media. However, in more recent years, there has been a partial return to the use of removable hard disks, such as the Iomega Jaz and Rev drives and disks and the SyQuest SyJet and Sparq drives and disks, and the Castlewood Orb drive and disk, among other models.
In fact it abbreviation is HDD.
Solid State HDD
solid-state drive (SSD) is a data storage device that uses solid-state memory to store persistent data. SSDs are distinguished from traditional hard disk drives (HDDs), which are electromechanical devices containing spinning disks and movable read/write heads. SSDs, in contrast, use microchips, and contain no moving parts. Compared to traditional HDDs, SSDs are typically less susceptible to physical shock, quieter, and have lower access time and latency. SSDs use the same interface as hard disk drives, thus easily replacing them in most applications.
As of 2010, most SSDs use NAND-based flash memory, which retains memory even without power. SSDs using volatile random-access memory (RAM) also exist for situations which require even faster access, but do not necessarily need data persistence after power loss, or use batteries to back up the data after power is removed.
A hybrid drive combines the features of an HDD and an SSD in one unit.
The pro's are:
- Faster start-up because no spin-up is required.
- No moving parts
- Less latency speeds results in faster application launch times.
The con's are:
- Higher costs.