Hard disk drives (called HDDs, as opposed to floppy disk drives or FDDs) allow users to store programs and data when power to the computer is turned off. Whether hard or floppy, these drives are essentially disks which, when spun by a motor, can have information stored on them read off by a laser or magnetic reader. The newest leap in on-board storage technology is the solid state drive, or SSD.
SSD: Non-volatile and no moving parts
The chief difference between an HDD and an SSD is the lack of moving parts. A hard disk drive requires a motor to spin the disk; an SSD has no moving parts. While the RAM memory typically used in laptop computers loses its contents when power is turned off, the memory in an SSD remains in storage even while not powered. Solid state memory is probably most familiar to people in the form of flash drives and compact flash chips. Over time, technology has increased the amount of data that can be stores in flash memory. It is now possible to have a flash drive or SSD with enough capacity to replace a moving hard disk drive.
Random access and no fragmentation
There are several advantages of an SSD over an HDD. SSDs start much faster, as there is no need to "spin up" the drive. Since there is no head moving across the disk to locate data, random access reading of SDD memory is much faster. SDDs do not suffer from the same file fragmentation problems as HDDs, which must be defragmented regularly to preserve top performance. Because SDDs have no moving parts, other than optional cooling fans, they are much quieter than HDDs. A wonderful benefit of the lack of moving parts is a much lower risk of drive failure from mechanical problems. Because of their ability to endure high altitudes, withstand vibration and extreme shock and a wide range of temperatures (up to 70°C), SDDs are particularly useful in notebook computers.
SSD pricing & value
At the moment the price of an SDD is about ten times that of an HDD, gigabyte per gigabyte. So a possibility worth considering is purchasing a notebook now with an HDD, and replacing it with an SDD in a year or so when prices drop. SDD drives use the same interfaces and, indeed, have the same form sizes as HDD notebook drives, and so replacing one with the other is as simple as installing a new HDD.
