What's the Difference Between Memory and Storage?

Are you confused about computer memory and storage? A lot of people are. Folks get confused about whether their programs and data are stored in memory, or whether the hard drive IS memory, or what memory is. Sometimes they just forget (bad memory joke).

Here is the difference between memory and storage. Think of a wood shop. The work table is where things happen, and the cabinet is where things are kept. When you want to screw together two pieces of wood, you take wood out of one cabinet and screws from another. The actual work takes place on the table, and then any extra parts are put back into the storage cabinet. And the finished work is saved on a special shelf in the cabinet.

Computers work in a similar way. Memory is the work table. The cabinet is your hard drive.

Memory is generally a dynamic space. That means it can change, and do so very fast. It is physically a chip containing a zillion on and off switches, and the combination of ons and offs is Aunt Bessie's sponge cake recipe, that picture of Uncle George, or the letter you wrote to your credit card company challenging a $300 charge you didn't make.

But those things are only in memory when you are working on them. That's why you have to save things on your computer. When you do that they go into storage, on your hard drive. The hard drive is a magnetic medium much like video tape. Little bits of stuff are magnetically arranged into patterns that represent -- did you guess? -- ons and offs, otherwise knows as ones and zeros. The disk revolves at a frantic pace and a little arm reads and writes onto it.

But that's too much information, right? What you need to know is that all your programs and data are stored on your hard drive. (Data are documents, pictures, sounds, videos, etc. Programs are computer code that make something happen. Your picture viewer is a program, and that picture of little Sara is data. The viewer program makes looking at that cute little girl happen.) Then when a program needs a file to work on, it is loaded into memory.

Why have both, when they essentially do the same thing? Two reasons:

• Memory dumps everything when you turn off your computer, but the hard drive retains what is stored on it.
• Memory is quite a lot faster than your hard drive. Even though it works reasonably fast when storing things, it is not practically fast enough to do calculations, draw a picture, or write a document. It is a mechanical device, so you have to wait for the parts to move, even though they seem to be cruising along pretty fast. But memory chips are just a lump of silicon with no moving parts. So the electrons that pass through them are very fast, depending on how well designed they are.

So next time you save something you'll know it is going to storage on your hard drive. But when you are working on it, it is speeding around in your computer's memory.