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What is the difference between memory and hard disk space?

Answer: Memory and disk space are two of the most widely-confused terms in the computing world. To understand how your computer works, you must first know the difference between memory and disk space.

The hard disk, sometimes called the "hard drive" (which is actually the mechanism that holds the hard disk), is a spindle of magnetic discs that can hold several gigabytes of data. Therefore, disk space refers to how much space you have available on your hard disk for storing files. When you save a document or install a new program, it gets stored on your hard disk. The more files you download, install, or save on your hard disk, the more full it becomes.

Memory, on the other hand, is not the same as disk space! Memory refers to the random access memory (RAM) inside your computer. RAM consists of small chips also known as memory modules. Your computer uses memory (RAM) to store actively running programs on the computer, including the operating system. For example, the operating system's interface and other processes get loaded into memory when the computer boots up. When you open a program like Microsoft Word, it gets loaded into the computer's memory as well. When you quit the program, the memory is freed up for use by other programs.

RAM can be accessed hundreds of times times faster than a hard drive, which is why active programs are loaded into RAM. Since only small amounts of data from hard disk does need to be loaded into the system memory at one time, computers typically have much more hard disk space than memory. For example, a 2012 computer may come with a 2 TB hard drive, and only 16 GB of RAM.

If your computer informs you that you don't have enough disk space to install a program, you will need delete files from your hard disk that you don't need or buy an additional hard drive. If your computer says there is not enough memory to run a certain program, you will need to upgrade your memory by buying more RAM. Knowing the difference between these two computer components can save you both time and money.

Published: January 24, 2005   —   Updated: July 18, 2012 — by Per Christensson

Answer from the PC Help Center