Corsair PC3-17000 Dominator GT 2GB, Crucial Technology PC3-17000 Ballistix 2GB and Kingston PC3-17060 HyperX H2O 2GB are a few examples of primary memory, often called RAM or Random Access Memory, that hold 2 gigabytes of data. Corsair, Crucial Technology and Kingston are the name of the brands. PC3 refers to the type of RAM, and the next number is the theoretical capable rate of data transfer.
Primary memory is used when the CPU works on currently active processes in a computer. Data stored in RAM is not permanent and is lost when a computer loses power. In computers such as servers, where data must be highly reliable, RAM may contain an extra data lane that is responsible for correcting minor errors and detecting major errors. While RAM is intended to be quickly accessed, it is not the fastest memory in a computer.
Before a computer processes data stored in RAM, the data is first moved to cache, which is much smaller but much faster memory. Most cache is split into a hierarchy of smaller, faster cache and larger, slower cache. Like RAM, cache also loses its data once the computer loses power, so in order to retain data, a computer must utilize secondary memory, which is a storage device such as a hard drive, DVD or flash drive.