Overclocking DDR?

[supercow228]

I noticed on TigerDirect there is a wide variety of memory in a few different categories. One category is Overclocking DDR (Ideal for gaming and graphics!). What is overclocking DDR, and why is it better than regular DDR memory? It costs more as well.....

 

[Morpheus]

I assume because you can up the frequensy or speed they are working at