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What’s the difference between memory (RAM) and a hard drive?

Computers have two kinds of storage. The hard disk drive retains data even when the power is off, and it stores the Mac OS (operating system, what makes it all work), all of your applications, data files, music, pictures, and so forth. The hard drive is semi-permanent storage (hard drives can and do fail, which is why we recommend backups). RAM is kind of like a scratch pad, where the computer puts everything it is working on right now. The RAM is forgotten when you shut down. All your work is saved to the hard drive. If you are retouching a photograph in Photoshop, it will be much faster if the computer can read the entire photo off of the hard disk and into RAM at once. If you don’t have enough RAM, the computer will have to keep constantly swapping data between the hard drive and RAM, and things will operate more slowly. Data in RAM can be manipulated very fast, while reading and writing to a hard drive is much slower.

Published March 24, 2009 12:00 PM
Last modified on June 16, 2009 5:19 PM

What’s the difference between memory (RAM) and a hard drive?

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