Memory is a built-in circuit (chip) that stores information automatically. DRAM means Dynamic Random Access Memory and is the chief memory utilized by the CPU to keep replica of files, application and other temporary files used by the processor whenever it is operating.

Whenever you observe a computer ad that says '1.2Ghz, 128Mb, 10GB Hard Drive etc, the 128Mb is actually the size of the DRAM memory in megabyte which is installed in your computer. One mega byte means 1 million bytes. Dynamic memory is a kind of memory that should be constantly revived in order to keep its contents.

Think of each bit position as if it were a small bucket. The amount of water in the bucket symbolizes the state of the bit stored there. If the bucket is more than half occupied by water, the bit is a 1. If it is not as much of that half full the bit is a 0. These buckets are leaky suitable to small holes in the bottom.

DRAM cell pour out because the cell formation used is small and inexpensive balance to static (non-leaky) memory. When you charge a cell, setting it to a 1 bit, it directly begins to lose charge. In a very short time the charge falls lower the half way mark and the 1 becomes a 0. Each cell must frequently be recharged with charge by the CPU or the self- refreshing circuit in newer DRAM devices.

The absorbent DRAM cells are less exclusive than SRAM cells which don't leak. If SRAMs were used, PC prices would go up obviously.

Random Access means that any locality in the memory can be examined or written instantly. It's like a CD, which is also a random access. When you choose a track on a CD it directly select that track and starts playing right away.

Serial Access on the other hand is similar to audio or video cassette. You can't enter any site you decide. You may have to reverse or fast forward past lots of stuff to get to the scene you want.