A Solid State Drive (SSD) has no moving parts, utilizing flash memory to store and access data. This is similar to a data stick. This gives the SSD some advantages over a mechanical Hard Disk Drive (HDD).
The primary advantage is speed. Without moving parts, the drive is able to access the date faster. This allows for faster boot times, which is one of the main reasons that SSDs are becoming favorites as Operating System Drives. Depending upon the model and the computer system running the drive, upwards of ten seconds can be saved from boot up time. The Windows 7 promise of an eleven second boot up (not including the bios startup time) was demonstrated using a SSD. Applications themselves, such as Word will load almost instantaneously.
Another advantage appreciated by computer enthusiasts is the low emission of heat. Without moving parts, namely a spinning disk, the heat generated by the drive is minimal. This allows for a cooler computer, which is very important in higher end gaming machines or for computer users who like to overclock their CPU.
The lack of moving parts also means that the drive is almost completely silent, which is something that can be appreciated by everyone. An HDD using spinning disks can get very loud, especially the higher RPM drives used in performance machines. An SSD is thus able to outperform even the higher RPM drives without any noise.
The high performance of SSDs and the added benefits of no noise and very low heat combine to make a versatile means of mass storage. As time progresses, it is beginning to see more and more use in mainstream consumer devices. It is only limited by the relatively small size and the price to size ratio. However, SSDs continue to be very useful for laptops and netbooks and as Operating System Drives on Desktops, and the consensus is that once storage capacity is upgraded on SSDs they will replace HDDs.