Full form of RAM is Random Access Memory.

It is primary storage memory. It holds data, instructions and three files of operating system. It is volatile. It's contents are entirely lost as soon as the electric supply is cut off. 

It becomes necessary in any computer system to transfer the contents of  RAM to the secondary storage device from time to time while working on the computer.

RAM means it is possible to randomly select and use any storage location for storage and retrieval of data. RAM is also called a read/write memory, because it can both.