SSD stands for Solid State Drive. You are probably familiar with USB memory sticks – SSD can be considered a larger and more sophisticated version of USB memory stick. Like memory stick storage, SSDs do not have moving parts. Rather, information is stored in microchips. In contrast, a hard disk drive uses a mechanical method to perform reads/writes on the storage plate. This difference is what makes SSD speeds so much faster.
The form factor of an SSD is similar to that of a regular hard drive. It comes in standard 1.8″, 2.5″, or 3.5″ sizes that can fit the space and connectors of a similarly sized hard drive. The connector used for these standard sizes is SATA. Smaller SSDs are also available that use mini-SATA (mSATA) and fit into a laptop's slot.