How does memory refresh work

Memory refresh is the process of periodically reading information from an area of computer memory, and immediately rewriting the read information to the same area with no modifications. Each memory refresh cycle refreshes a succeeding area of memory. Memory refresh is most often associated with modern dynamic random access memory. However, several early computer memory technologies also required periodical processes similar in purpose. These technologies include delay line memory and Williams tube.

Compare with magnetic core memory where each memory cell needs to be refreshed after being read, but periodical refreshes are not necessary. Also, see static random access memory which is used in similar applications as dynamic random access memory, but does not require refreshing (hence labelled static as opposed to dynamic).

"Here are the various used ram memory we have in stock."
16mb EDO used Ram Memory	32mb EDO used Ram Memory	64mb EDO used Ram Memory
32mb Sdram used Ram Memory	64mb Sdram used Ram Memory	128mb Sdram used Ram Memory
256mb Sdram used Ram Memory	512mb Sdram used Ram Memory	1gig Sdram used Ram Memory
128mb DDR used Ram Memory	256mb DDR used Ram Memory	512mb DDR used Ram Memory
128mb Laptop used Ram Memory	256mb Laptop used Ram Memory	512mb Laptop used Ram Memory

Acer Memory	Apple Memory	Cisco Memory	Compaq Memory	Dell Memory	Fujitsu Memory	Gateway Memory
HP Memory	IBM Memory	Intel Memory	Sharp Memory	Sony Memory	Sun Memory	Toshiba Memory