I help a lot of people with their computers: laptops, desktops, servers, you name it! With the diverse range of computer and life experience of my end users, I've noticed one topic keeps coming up: memory versus storage.
It generally starts out with seemingly simple questions: "If I need more memory, shouldn't I just clean up some of my documents or photos?" or "I'm running out of space to store my music, do I need more memory?" Sometimes computer terms can be confusing, ambiguous or just plain gibberish. The nice thing about the memory versus storage confusion is that it can be resolved pretty easily.
First, there are two types of memory: volatile and non-volatile. Volatile means that when you remove power from the device the information that is stored in that memory is forgotten, generally immediately. Non-volatile means that when the power is removed, the information stored there is remembered. When talking about memory, you are generally talking about physical chips - semiconductors. Your computer has a many different types of memory, including different levels of cache associated with your CPU (very fast, volatile), the memory where applications sit while they are being executed (fast, volatile), and the NVRAM or BIOS chip on your computer (the NV in NVRAM stands for non-volatile). When your computer first turns on, it reads the settings from your NVRAM/BIOS, and unless something modifies, erases or changes the information stored on this chip, it will be remembered even if you turn off and unplug the computer. Conversely, when you turn off your computer, all of the cache memory and primary memory resets to all zeros - it forgets everything.
If all of your volatile memory is cleared out when you shut down your computer, where does everything come from?
Your operating system (Windows, Mac OS, Unix, Linux), your applications like Word, Pages, Excel and Numbers; and all of your music, photos and documents are stored in storage. Typically, memory is very high-speed, whereas storage - hard drives, tapes, optical media such as CDs and DVDs and even USB thumb drives, are much slower, to varying degrees. When we talk about "cleaning up documents" or "removing applications," what we mean is freeing up storage space on a hard drive (internal/inside, or external/outside), a USB memory stick, or a re-writable optical device.
Cleaning up memory is a different story.
In today's modern world of multitasking computers and operating systems, computers can do more than one thing at a time. It can play your favorite songs on Pandora "in the background," while you browse the web, a clock updates on-screen, and your favorite mail program watches for new incoming mail. All of these things, and much more, can happen at the same time. How? Multitasking. Where do these programs reside when they are active/running? In memory. When an application is not running (for example, when you're not running Adobe Photoshop), that application is stored in storage - typically on your hard drive. When you run (execute) the application, it is loaded into memory, where the CPU then executes the program step-by-step. Modern CPUs can slice up the time (or multitask), so they might spend part of their time updating the clock, part of the time checking for mail, notifying you of calendar events, and the bulk of the time displaying ("rendering") a YouTube video, or streaming music over the Internet. Multiple-core, or multiple-thread CPUs can actually do more than one thing at the same time, rather than simply divide its time between different tasks; it's like having two or four people doing twice or four times the work, rather than just having one person split their time between two or four tasks.
In the end, the CPU executes the programs loaded into memory, and even temporarily stores and manipulates application data (such as photos you are display or editing, music you might be listening to, or documents you may be working with) in memory. The volatility of memory is the reason why you should always save your work as often as you can, or use auto-save features, because if the power goes out, or Fido pulls the plug, unless your application data is saved to storage, the memory forgets that information, and it's lost.
As a reminder: the best way to avoid the power outage issue is to purchase and use a UPS in-line. A UPS (or UninterruptiblePower Supply) is simply a device that plugs into the wall, and the computer plugs into the UPS. The UPS has a battery, and when the power goes out, or goes lower than normal ( a brown-out), a good UPS will condition the power so that the computer continues to run - even after the lights have gone out. A high-quality UPS with a decent battery (measured in Volt-Amps or VA) and the AVR technology (Automatic Voltage Regulation) can even actively protect your computer and other attached equipment from voltage spikes, giving these devices extended life - which means less money on repair bills down the road. Having your computer and monitor connected to an appropriately-sized UPS also means that you will be given enough time to save your work from memory into storage, so you won't lose anything; and for shorter outages, you can keep right on working. With a large enough UPS, you could keep working for hours, giving you enough time to cut over to a generator, if required.
Having said all that, if a computer person tells you that you need more memory, they typically mean that you need more volatile memory for running applications - generally because you are running so many things at the same time: operating system, web browser, mail program, calendar, anti-virus, anti-spyware, photo editing suite, you name it. Any time additional programs are running at the same time - and this number tends to increase as you load more programs - you are using more of this volatile or executable memory. There are ways to close down applications, or disable background tasks you no longer need. Some applications are "clean," and do not automatically ship with tasks which start-up (and use memory) whenever you sign into your computer - while other applications do eat up memory. Some applications like your anti-virus (which must always be resident/running to keep you safe) and your default system clock are always running, and should probably always keep running; while other applications, like a "quick loader" for your favorite application that you use once or twice a year, might be eating up your precious memory, and could be disabled.
Unless you are running out of storage space on your hard drive, you don't need to remove documents or uninstall applications, unless you feel like housecleaning or re-organizing. Also, remember that hard drives will eventually fail, leaving you with some or all of your data and applications potentially lost. Specifying, installing and using a backup system (hardware and software) can be as inexpensive as a $40 backup utility used in conjunction with a $100 external USB hard drive. You tell the backup software to copy the contents of your hard drive to the external USB storage device at regular intervals (once a day is best, once a week might be acceptable for you, depending on how frequently you create and change data on your internal hard drive) and so when your internal hard drive fails, you can replace that hard drive and restore from your external backup. This will save you tons of frustration and, as a technical person, I don't enjoy telling folks that their hard drive has failed, and that all of their data (pictures, music, spreadsheets, documents, presentations and e-mail), settings and applications are lost. Think about a backup solution if you don't have one.
I realize this is a lot of ground to cover, but to recap:
* "Memory" typically means the volatile memory in your computer, which clears when you shut it down
* "Storage" is where your applications and all of your data is stored, so it can be loaded into memory when needed.
* A surge protector is a must for all computer equipment, but a good UPS will provide you additional safety and convenience.
* If you're not backing up your internal storage to an external storage device, you are risking the loss of everything stored there.