RAM (Random Access Memory). This is where the data being processed (open documents, for example) and the instructions of the program being used are stored. The RAM is a volatile (temporary) memory that is completely erased whenever the computer is turned off.
The documents we create on the computer (for example, when we write a text) are stored in the RAM and are copied onto a disk (which, contrariwise to the RAM, is a permanent memory) only when the user expressly instructs the computer to save them.

RAM storage capacity is measured in megabytes (MB); that is millions of bytes (one byte is the space required for storing one keyboard character). The rate at which information is written into or read from the RAM is measured in nanoseconds (ns = 0.000000001 or one-billionth of one second in U.S. usage). Today's computers are normally supplied with 128 or 256 MB of RAM. If the RAM is insufficient to contain all the data the computer needs, the machine performs an operation called a swap, whereby, in order to free space, a part of the contents of the RAM is temporarily copied onto the hard disk and retrieved later, if needed. Since the disk read/write access time is much higher than the time needed to read or write a RAM, it is evident that a swap will tend to slow down all the operations. To limit swapping, all that need be done is add more RAM.
RAM storage and microprocessor speed (clock rate) are the two parameters that most influence computer performance.

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