Computer uses different kinds of memory to operate efficiently. Memory is required to store the information which may be required for current operations or it may be useful for later usage. These memories can be classified in volatile or nonvolatile, random access or sequential access, virtual memory, programmable memory, flash memory. For generic purpose, computer memory is referred to RAM which is random access memory. It is used to support computers current operations. This memory is available and utilized to store information while computer is powered on, once power is switched off, information from memory gets erased automatically, and makes it ready to be available once computer is powered on again. This is the reason; it is called volatile memory as well. It is written and accessed randomly and that is where it got its name from.
There are two types of RAM available now days, static and dynamic. Data is stored bit by bit as the state of flip flop in static memory whereas in dynamic memory it is stored as charge in capacitor. Both SRAM and DRAM are volatile however disks, tapes are form of permanent storage.
RAM is very important part of any computer system; it determines that how much complex operations can be performed simultaneously or how any applications can work in parallel. Whenever the computer is powered on, first of all it stores minimum functions of Operating system in RAM before it hands over control to the operator. Whenever any application is launched from Operating system, the same process follows. Any operations on data via these applications are performed by CPU, using RAM. However RAM is not the most neared memory a processor uses, that memory is called cache and that is directly attached to CPU.
To explain this, let us understand how RAM works. Computer is using disks, tapes for storing data permanently. However while any operations needs to be performed on this data like file open, file edit; data needs to be stored in RAM so CPU can perform all this operations. Once these operations are executed, data can be saved back to permanent memory. RAM is expensive so as precious to be used, for more files to be opened or more applications to work upon, more RAM is required.
Another term used very frequently is swap memory. As explained earlier, RAM is very expensive memory in comparison to permanent storage. There is way to use this permanent storage which can work RAM for completing the operations while RAM is already consumed. Operating system can define some part of disk as virtual memory which can be used to swap the RAM for completion of processing of data. Processor thinks this swapped memory as part of RAM as it is virtualized to do so. However there is a negative side of it; more swap memory usage, makes computer run slower.
Typically RAM is a volatile memory however research is going on to makes it nonvolatile so as to preserve data stored in it while computer is powered down. RAM is not performing any operation directly however more RAM makes computer faster as it helps CPU to perform complex operations faster.