What is an SSD?

Solid state drives (SSDs) are the fastest storage devices currently available. They replace the mechanical hard disk drive inside your computer or laptop to increase performance and speed up loading times. SSDs also consume less power and are more resistant to physical shock, run quieter than HDDs, and have faster input/output rates with lower latency.

An SSD consists of memory chips installed on a circuit board, typically a motherboard. Crucial's parent company Micron manufactures the flash memory chips in-house on silicon wafers, similar to how it makes its computer memory. The memory chips record a charge or lack of one on floating gate transistors in a grid pattern to store data. The memory chips are organized into a block, which is then read and written by an SSD controller.

The controller keeps track of where the data is stored, reducing the amount of work required by your computer to access and use it. This reduces the time it takes to load a spreadsheet program from your hard disk, or transfer files between hard drives and the RAM that acts as your computer's bank of available workspace.

The processor then uses the memory to "run" the program. The process of accessing and using data from your storage device can be up to three times faster than it is with a hard disk drive.

In addition to the speed advantages, an SSD is more resistant to vibration or abrasion than a hard disk drive, so it can be used in mobile devices, such as tablets and laptops, where it can be exposed to rough treatment or bumps. The lack of moving parts also contributes to an SSD's increased resistance to shock, and an SSD may have a metal casing to further protect the internal components.

Most SSDs are built to withstand sudden power loss, preserving the contents of the drives and data until the device is restarted. The underlying technology of an SSD may have built-in capacitors to provide protection in the event of a power outage, and some enterprise-class SSDs are designed with supercapacitors to keep certain blocks of data intact for longer periods of time.

Many SSDs are designed with different form factors to fit inside different types of computers and laptops. The 2.5-inch form factor found in most laptops is the most common, while smaller mSATA and M.2 form factor SSDs are popular in notebook computers. Some SSDs support a range of logical device interfaces, such as Advanced Host Controller Interface and NVMe, to help operating systems work with the drives.

The WD My Passport Ultra is a great choice for a portable SSD. It's slim, light and has a USB-C connector that fits into most modern Macs and PCs. You can also use a USB-C to USB-A adaptor or cable for older machines. It includes a software utility and a five-year warranty, which is pretty good for an SSD of this price. There is an 'Pro' model, which doubles the speed of the SSD for those who want to game on their PC with a super-fast external drive, but that will cost you about 30% more.