SDRAM is very protective of its data bits, storing them each in a separate capacitor. The benefit of this is the avoidance of corruption and the maintenance of "pristine" data. The drawback is that those same capacitors that are so useful at storing the SDRAM bits also happen to be very bad at keeping electrons in check; the result is where the Dynamic part of the name comes in, as refreshes are required to maintain data integrity. Once all of that dynamic refreshing and storing are done with, the result is a dense package of data, one of the densest in the business world.
