What is RAM (Random Access Memory) and its usage?

It is primary storage i mean volitile memory for fast accessing and temporary storage has its use

Random-access memory (RAM /ræm/) is a form of computer data storage. A random-access device allows stored data to be accessed directly in any random order. In contrast, other data storage media such as hard disks, CDs, DVDs and magnetic tape, as well as early primary memory types such as drum memory