RAM (Random Access Memory) : RAM is the most common form of memory chip; an integrated circuit comprised of transistors and capacitors. The "random access" denotes that the CPU can retrieve and store information in any order required. The RAM chip therefore provides the CPU with a temporary storage medium, where it can process electronic data. The variants SRAM (Static RAM) and DRAM (Dynamic RAM) both hold data but do so in a different ways.
DRAM (Dynamic Random Access Memory) : DRAM is one the most common types of memory, it can hold information for a short period but must refresh regularly. It is used to temporarily store information.
SRAM (Static RAM) : In contrast to DRAM, Static RAM does not need to be refreshed periodically as the transistors inside of the chip continue to hold stored data until the power supply is cut off. This means that data can be written and read more quickly than in a DRAM memory chip.
SDRAM (Synchronous Dynamic Random Access Memory) : synchronizes the input and output signals with the system board. While DRAM responds as quickly as possible to changes in control inputs, SDRAM synchronises with clock signal of the system bus. This enables higher speeds for SDRAM memory chips when compared with standard DRAM.
DDR memory : DDR stands for Double Data Rate, and runs at twice the speed of normal SDRAM.
Flash Memory : Flash memory is a solid-state, non volatile, rewritable memory which acts like a combination of RAM and a hard disk. In the event that the power is lost, the data is retained in the memory. It is high speed, durable, and has low voltage requirements.