An SSD (solid-state drive or solid-state disk) is a storage device that stores persistent data on solid-state flash memory. SSDs actually aren't hard drives at all, in the traditional sense of the term, as there are no moving parts involved. Instead, an SSD has an array of semiconductor memory organized as a disk drive, using integrated circuits (ICs) rather than magnetic or optical media.

 

This arrangement has many advantages. Data transfer to and from solid-state drives is much faster than electromechanical disk drives. Seek time and latency are also substantially reduced. Users typically enjoy much faster boot times as well. In general, SSDs are also more durable and much quieter, with no moving parts to break or spin up or down. SSDs do, however, have slower write times and a set life expectancy, as there is a finite number of erase/write cycles before performance becomes erratic.

Development and adoption of SSDs has been driven by a rapidly expanding need for higher input/output performance. High performance laptops, desktops or any application that needs to deliver information in real-time or near real-time can benefit from SSDs.
  
Sources:  
itworld.com
techtarget.com