Which memory type requires frequent refreshing every few milliseconds?

Dynamic RAM (DRAM) requires frequent refreshing every few milliseconds because it stores each bit of data in a separate capacitor within an integrated circuit. Capacitors tend to lose their charge over time, which means that if the data is not refreshed regularly, it could be lost. This refresh cycle is what differentiates DRAM from Static RAM (SRAM), which retains its contents as long as power is supplied and does not need to be refreshed.

In addition, the term DDR, which stands for Double Data Rate, is a technique used in memory types including DDR3. While DDR memory types are based on DRAM technology and can still have refresh cycles, the fundamental requirement for frequent refreshing applies specifically to DRAM itself. Thus, the correct answer linked directly to the requirement for refreshing memory every few milliseconds is DRAM.