Mian Memory: Main memory is the internal part of computer.It is used to store data and instructions that are currently in use.It is a temperory stoarge.It is directly accessible by the CPU. It is volitile. Its contents are lost when computer is switched off. So data and programs can not be stored permanently into it. Ram is an example of main memory. Man Memory is very fast than secondary memory.This is because the main memory is located on the motherboard. CPU can directly stroe & retreve data to and from it.The secondary memory is located outside the motherboard. Main memory is expensive than secondary memory. Secondary Memory: This secondary stoarge is used to store information permanently for later use. It is an external part of the computer. A large amount of data and programs can be stored into it. Its stoarge capacity is up to Gegabytes for personal computers. Hard disk and floppy disk is the example of secondary memory.