The best way to explain why SSD is a buzz acronym for the solid state drives we want in our notebooks is to show the problems with practically stone-age spinning hard drives inside most computers (and iPod classics). Since they have platters w/ magnetized surfaces that spin fast as they read or write data—think record player—they can be quite slow, and are really fragile. Anyone who's owned a computer or iPod knows (or will one day learn) that if the read/write head bumps into the platter, it's all over. SSDs aren't like that at all.
SSDs have no moving parts, so seek time is drastically reduced. No spinning=less battery vampirage, so your laptop lasts longer too. And finally, the lack of a deadly read-write head means you can drop your SSD-powered lappy with far less chance of weeping. Right now, SSDs are usually made with either SDRAM (like RAM used in computers) or NAND flash (like in thumb drives, iPod nanos, etc.). Flash is more common, since it doesn't need a battery even though it's slower. Problems: Gig for gig, SSD is way expensive. The beefiest you'll be able to get soon is 128GB (or maybe 256GB)—but the current 64GB 2.5" SSDs go for $1,200 and up. Still got questions?