In a PC or a laptop there are various kinds of hardware on it. One is memory or RAM (Random Access Memory). Memory is hardware that stores data to be accessed by a computer processor. Data can be accessed at random with the same speed by computer processor that is us. The data stored in memory is only temporary, this data will be lost if your computer does not turn on. Data available in memory can be accessed faster than data stored in the hard drive.
At this time most computers or laptops already use DDR2 and DDR3 memory types. Before the year 2000 there are very many computers that use memory type SDR (Single Data Rate), but after 2000 SDRAM was left and people turn to the type of DDR (Double Data Rate) is capable of doing a transfer rate twice faster.
SDRAM
DDR1
DDR2
Each type is an development from previous type, and the latest versions generally have a higher data rate and require lower power. DDR2 is theoretically have a data rate of 2x with the same specifications than the DDR (DDR1). DDR3 also has advantages over DDR2, such as higher bandwidth, latency that more superior, higher performance at lower power, and better for low-power devices such as laptops. Each type of RAM is not compatible with each other and designed with a different slot.
