Dynamic random-access memory

Dynamic random access memory is the most commonly used form of RAM.

DRAM is called dynamic (or active), because it must be refreshed all the time or it will lose the data which it is supposed to be storing. Because it loses data when power is removed, DRAM is called volatile. This word comes from the Latin adjective volātilis, which means "flying, fleeting, transitory".

Refreshing DRAM means reading the data from the DRAM and directly writing them back to the DRAM. DRAM is made up of millions of very small capacitors. Each of these capacitors has a transistor to let energy in and out. The capacitor slowly loses energy, and if the DRAM is not refreshed, in the end one or more of the capacitors will let so much energy out, that for example a 1 will become a 0, so data will be lost or corrupted. Almost all computers refresh their DRAM many times per second.