The word 'random' means that the computer can access any memory cell without accessing all cells sequentially. That is, a memory is said to be random access memory if any part of it can be accessed directly (randomly) for reading or writing data in the same time irrespective of its location. In other words, access to this memory is independent of physical storage location of information on the medium. RAM is volatile as any interruption in power supply results in loss of data in RAM. The contents of the memory remain there as long as electrical current is available to sustain the memory's pattern of positive and negative charges which represent the two bits 1 and O.lf power fails, all the contents in the memory will be lost.
Types of RAM
The various types of RAM are DRM, SDRAM, static RAM, Vide/) RAM and flash RAM.
1. Dynamic Random Access Memory (DRAM)
It is one of the least expensive RAMs. But it requires frequent power refreshing to retain memory contents.
SDRAM (Synchronous Dynamic Random Access Memory) is a generic name for the types of DRAM that are synchronised with the clock speed of the processor. The speed of SDRAM is measured in terms of Megahertz. If the speed of the SDRAM and processor is optimised, the processor can improve its performance.
3. Static RAM
Static RAM does not need frequent power refreshing as is required for DRAM. Hence, it is much faster than DRAM. But, it is more expensive than DRAM.
4. Video RAM
It is used to storE: data for the video display monitor. It is actually a buffer between the processor and the monitor.
5. Flash RAM

Flash RAM or flash memory is a non-voLatile memory. It can be erased and reprogrammed. It is used in PC cards of notebook computers, digital camera, cell phones, embedded controllers etc.