What is Random-access memory?
{{unreferenced|date=August 2012}} [[File:4GB DDR3 SO-DIMM.jpg|thumbnail|A stick of DDR3 RAM that is for laptops]] '''Random-access memory''' (or simply '''RAM''') is the [[computer memory|memory]] or information storage in a [[computer]] that is used to store running [[computer program|programs]] and [[Information|data]] for the programs. Data (information) in the RAM can be read and written quickly in any order. Normally, the random access memory is in the form of [[computer chip]]s. Usually, the contents of RAM are accessible faster than other types of information storage.However, RAM is volatile, which means that every time the computer is turned off, all the data in the RAM is lost. The alternative to this, [[Non-volatile random-access memory]] (NVRAM), which keeps its data without using power, is more expensive and works slower, so it is used in smaller amounts. Since the late 20th century, RAM uses transistors, usually [[MOSFET]]s, to store data. Before that, [[magnet]]ic memory was the usual kind. == Different types of RAM == [[Dynamic random access memory]] (DRAM) is the majority in computers. Modern computers use several types of DRAM. Before 2002, most computers used single data rate (SDR) RAM. Most computers made since then use either double data rate (DDR), DDR2, DDR3, or [[:en:DDR4_SDRAM|DDR4]] RAM. The later types allow stored data to be moved and used more quickly, so that the computer's processor can keep working quickly without having to wait for data as long or as often. Different kinds of RAM usually will not work together in the same computer. Most computers can only use one kind of RAM. Some can use a small number of different kinds. Different kinds of RAM often have differently shaped connectors. This limits which RAM chips a particular [[computer model]] can use. [[Static RAM]] (SRAM) needs power to keep its data, but does not need the computer to be active. Some SRAM chips are battery-backed. This type has a built-in [[battery]] to make sure no data is lost if the computer is turn