A.k.a. “solid-state hard drive.” A large-capacity data storage device based around an array of flash memory chips instead of rotating magnetized platters as in a “mechanical” hard drive. Solid-state hard drives have no moving parts, and therefore use less energy, are quieter, are more durable, and do not require fans for cooling. In most cases they are faster than mechanical hard drives because there is no read or write head that has to move to retrieve or lay down data. Conversely, solid-state hard drives are generally more expensive than mechanical drives, and are currently limited in capacity compared to mechanical drives.
Solid-state hard drive performance diminishes over time (flash memory can only be written and read a certain number of times), but the drives compensate to maintain optimized performance over their lifespan. It is likely that a solid-state drive will be obsolete before its performance deteriorates enough to become an issue.
A solid-state “drive” may consist of a bank of chips mounted on a motherboard, a bank of chips mounted to an expansion card, or a bank of chips enclosed inside an external enclosure.