A solid state drive is a hard-drive that uses solid state physics instead of relying on electromechanical moving parts like most current harddrives do. For example, there are solid drives based on flash, DRAM, SRAM, etc. RAM based solid state drives are also called RAM-disks, and use internal battery to ensure data persistence. Flash drives are less expensive, however, they are also slower than RAM-disks.
Because solid state drive doesn't require moving parts, they are quiet, more durable, and of course faster. However, they are also more expensive and have a lower storage density.
Hard"ware` (-wâr`), n. Ware made of metal, as cutlery, kitchen utensils, and the like; ironmongery.
Webster Unabridged