Single In-Line Memory Module (SIMM)
The Single In-Line Memory Module (SIMM) provides limited memory and cannot hold large amounts of data. It is one of the oldest types of memory and is seldom used today.
Dual In-Line Memory Module (DIMM) or SDRAM
The Dual In-Line Memory Module (DIMM), also called SDRAM, has more capacity than the SIMM but is still relatively limited. It is fairly cheap and supported by many types of motherboards.
Double Data Rate (DDR) DIMM or SDRAM
The DDR DIMM or DDR SDRAM is an upgraded version of the DIMM.
It is faster and has a greater memory , but usually requires a motherboard with a special socket for installation. It is more compatible with AMD processors, but it works with Intel processors as well. It is the most commonly used computer memory today.
Rambus (RIMM) RAM
The Rambus (RIMM) or RDRAM provides the fastest speed and the greatest memory capacity. It is designed exclusively for Pentium 4 computer processors. It is also available in smaller versions for use with laptops.