SSD (or Solid State Drive) is the new trend at the moment in the world of computers, held back by its high introductory prices. As those prices keep coming down, holding on to a traditional hard drive is not a wise decision any more. In layman terms, SSDs are fast and silent, and consume less power.
Why would anyone ditch his/her trusted hard drive and go for a SSD? Because the time saved will deem it a worthy decision. Booting Windows/Mac OS from a SSD takes around 30% of the same time needed when booting from the usual hard drive with its rotating platters and moving parts. Launching applications is nearly instantaneous, and you do not torture yourself with the constant noise coming from the hard drive with its spinning platters.