RAM is an abbreviation for Random Access Memory. RAM is the computer's main memory. The computer uses RAM constantly to temporarily store information while it is working with it. The photo above shows what a SDRAM DIMM memory module looks like. SDRAM stands for Synchronous Dynamic Random Access Memory. SDRAM runs synchronously, (or at the same pace), with the processor's front side bus. A bus is simply a connection between items on the motherboard. The speed of the memory, or its data transfer rate, is how fast the data can travel between the RAM and the processor. The speed is measured in MHz, (or megahertz). The memory module shown above is a DIMM module. DIMM stands for Dual In-line Memory Module. The term DIMM has nothing to do with the speed or capacity of a memory module. It simply refers to the way the module is designed. DIMM modules consist of several DRAM chips. DIMM modules have separate contact points on both sides of the module. Below is a picture of a single DRAM memory chip.

Single Memory Chip

Some memory is capable of checking for errors. This memory is called ECC, (or Error Correction Code), memory. If a computer has a lot of memory, it can store a lot of temporary data and operate faster. People with good memories also retain more information and do things faster, because they don't waste a lot of time trying to remember things. Computers commonly have 512MB to 1GB of memory.

The DDR SDRAM memory module replaced the SDRAM memory module. DDR stands for Double Data Rate. SDRAM runs at the same pace the system clock runs. DDR SDRAM runs at double the pace the system clock runs. After DDR SDRAM came DDR2 SDRAM. DDR2 SDRAM runs at four times the pace the system clock runs. Below is a picture of a DDR2 SDRAM DIMM memory module.