What is Memory or RAM

MemoryMemory or RAM is the temporary working memory that your computer uses to perform calculations and manipulate files. When you open a document, it is copied from the hard drive into RAM. As you and your word processor work on the file, the modified copy exists only in RAM. When you save the file, it is copied from RAM back to the hard drive, or permanent storage. It is also the place in a computer where the operating system, application programs, and data in current use are kept so that they can be quickly reached by the computer's processor.
Two basic types of RAM
Dynamic RAM – the more common type but need to be refreshed thousands of
times every seconds because its made up of millions of transistors and capacitors.
Static RAM - RAM does not need to be refreshed, which makes it faster; but it is
also more expensive than dynamic RAM. It is mainly used in cache.

Other types of RAM
FPM DRAM: Fast page mode dynamic random access
EDO DRAM: Extended data-out dynamic random access memory
SDRAM: Synchronous dynamic random access memory
DDR SDRAM: Double data rate synchronous dynamic RAM
RDRAM: Rambus dynamic random access
Credit Card Memory
PCMCIA Memory Card: