To one generation, DDR means Dance Dance Revolution, but to those who don't spend time in arcades, it means double data rate. DDR memory was a natural evolution in the computer industry that grew out of increases in processor speed. As processors got faster, they needed more data to make use of that speed; otherwise your computer would end up doing nothing really, really fast while it waited for memory. There were ways around it, such as caches, but the only real solution was to speed up memory. The problem was that memory clock speeds were already as high as they could go at the time. DDR resolved the issue by transferring two bits of data every cycle, effectively doubling the speed. Faster speeds mean fewer processor stalls, and more use from that powerful processor. DDR comes in several speed grades, from the slowest PC1600 DDR all the way up to PC3200. Many computers still use DDR RAM, even though there are later standards, and it's easy to find from reliable sellers on eBay. Put the technology revolution to work in your computer.