Updated: 07/06/2021 by Computer Hope
DDR4 stick of memory

Computer memory is any physical device capable of storing information temporarily, like RAM (random access memory), or permanently, like ROM (read-only memory). Memory devices utilize integrated circuits and are used by operating systems, software, and hardware.


When information is put into memory it is written. When information is grabbed from memory it is read.

What does computer memory look like?

Below is an example of a 512 MB DIMM computer memory module. This memory module connects to the memory slot on a computer motherboard.

Computer memory

Volatile vs. non-volatile memory

Memory can be either volatile and non-volatile memory. Volatile memory is memory that loses its contents when the computer or hardware device loses power. Computer RAM is an example of volatile memory. It is why if your computer freezes or reboots when working on a program, you lose anything that hasn't been saved. Non-volatile memory, sometimes abbreviated as NVRAM, is memory that keeps its contents even if the power is lost. EPROM is an example of non-volatile memory.


Computers use both non-volatile and volatile memory.

What happens to memory when the computer is turned off?

As mentioned above, because RAM is volatile memory, when the computer loses power, anything stored in RAM is lost. For example, while working on a document, it is stored in RAM. If it were saved to non-volatile memory (e.g., the hard drive), it would be lost if the computer lost power.

Memory is not disk storage


It is very common for new computer users to be confused by what parts in the computer are memory. Although both the hard drive and RAM are memory, it's more appropriate to refer to RAM as "memory" or "primary memory" and a hard drive as "storage" or "secondary storage."

When someone asks how much memory is in your computer, it is often between 1 GB and 16 GB of RAM and several hundred gigabytes, or even a terabyte, of hard disk drive storage. In other words, you always have more hard drive space than RAM.

How is memory used?

When a program, such as your Internet browser, is open, it is loaded from your hard drive and placed into RAM. This process allows that program to communicate with the processor at higher speeds. Anything you save to your computer, such as a picture or video, is sent to your hard drive for storage.

Why is memory important or needed for a computer?

Each device in a computer operates at different speeds and computer memory gives your computer a place to quickly access data. If the CPU had to wait for a secondary storage device, like a hard disk drive, a computer would be much slower.

Types of memory

There are several types of memory for computers. They are listed below.


ROM is separated into three categories:


There are six types of RAM:

These types of memory all fall into the general categories of SIMM or DIMM.

Computer acronyms, GDDR, Memory capacity, Memory terms, Optane memory, Primary storage, Processing device, RAM, ReadyBoost, TSR, Virtual memory, Volatile memory