RAM, Memory, Hard Disk, Oh My!

I am often asked what's the difference between "RAM", "memory" and "hard disk space." Without going into a whole lot of TechnoBabble, "RAM" and "memory" are interchangeable but "hard disk space" is different. Think of "RAM" or "memory" as "short-term memory." By way of an analogy, RAM/memory is like someone rattles off a phone number that you need and you say it to yourself just long enough to remember the numbers when dialing your phone. By contrast, think of "hard disk space" as a notepad where you write down the number instead of simply trying to remember the number. It takes longer to write that number down but you now have a permanent record that you can store for a long time. In short, a "long-term memory."

Reading from/writing to RAM/memory is many times faster than writing to a hard disk. When faced with a lack of actual RAM/memory, modern day computers compensate by using hard drive space to temporarily store data and this is known as "virtual memory." This will allow your computer to do more things (e.g. running additional programs) even though it really doesn't have enough physical RAM/memory to do so. The drawback, however, is that reading from/writing to a hard disk is much slower than reading from/writing to RAM/memory. As a result, the additional programs will load and run but you'll notice quite a bit of lag or lack of responsiveness. On the Mac, you may even notice the dreaded "beachball" or "pinwheel". If you see this often, consider augmenting your Mac's RAM/memory.