Are you all caught up on what an operating system (or OS) is? If not, read What’s an “operating system” (or “OS”)?

Do you know what OS runs your computer? Do you even care? Well, if you ever seek help with your computer or otherwise discuss it with people, it’s a question you will be asked.

“Do I need to care what OS I have?”

There are lots and lots of OSs (read that as “operating systems”) out there, created at different times by different people for different computers (where “computers” includes every computerized gadget you can think of: mobile phones, tablets, digital watches, your video recorder, your newfangled washing machine…)

Many of these OSs have names a normal person has never heard of; you’ll never need to give them a second thought. You can happily use your car’s navigation system without ever wondering what OS makes it work.

But you should know what OS is running your computer. Why?

When you ask people for help with your computer, “What OS are you running?” (that is, “What’s the OS on your computer?”) may be the first thing they ask you in return.

Similar to the above, when you look up information on how to perform some task on your computer, the answer may differ depending on your OS. You’ll need to look for the answer that’s right for your OS.

And there’s this, too: When you buy or otherwise add a new application (“app” for short) to your computer, it has to be an app that is made to work with your OS. If it’s made to work only with some other OS, it won’t work on your computer.

“All right, then. So, what OS do I have?”

I can’t answer that for you! But I can tell you how to find out easily.

You want to know two things: Your OS’s name and its version. The version comes into play because an OS is typically updated again and again by its creator (to fix problems, add new features, and so on);

It’s pretty much the same thing as knowing the make and model of your car. Your know your car is a Ford Taurus, sure, but for the purpose of repairs, accessories, and just a general sense of whether it’s time to consider a newer model, you’ll all want to know whether that Taurus is a 1998 Ghia, or 2005 SE sedan, or 2007 SE sedan, or whatever.

OS names

Like any other product, an OS will have a name. You may have heard of some OS names: OS X (lately renamed “macOS”), Windows, iOS, Ubuntu, and others.

These names can refer to whole “families” of OSs. For example, “Windows” covers a number of separate OSs, with names including Windows 95, Windows XP, Windows 7, and more.

OS versions

People rarely create software and say, “There, I’m done with it!” Especially with a huge piece of software like an OS, which typically requires years of work by teams of people to create, programmers will keep improving things. Each new version of the product is called just that: a version.

A new version may get its own descriptive name, but versions are typically referred to by numbers, such as Version 1 for a new product, followed by a later Version 2 with new improvements, and so on. (A Version 1 might be written as “Version 1”, “Ver. 1”, or “v1”.)

Often, software versions will use decimals – even multiple decimals – to refer to lesser changes. For example, after releasing the 7th major version of a software product, labeled Ver. 7.0, a company may plan a big Ver. 8.0 with lots of new features. But before that, it may release a Ver. 7.1, then 7.2, and so on, with only small improvements and perhaps some fixes for newly-discovered problems. Between 7.2 and 7.3, there may even be a 7.2.1, then 7.2.2, and so on, with those fiddly little numbers representing very minor changes.

Check your OS!

If you know where your computer comes from, the OS is probably a given:

If you have a desktop or laptop computer from Apple

These include computers from Apple’s line of Macintosh (or “Mac”) computers, including models with the names iMac, Mac mini, iBook, MacBook, MacBook Pro, MacBook Air, Power Mac, and PowerBook.

The OS included with Apple computers is also made by Apple and is called macOS (pronounced “mac Oh Es”). That’s a new name; versions released between 2012 and 2015 were called OS X. (That’s pronounced “Oh Es Ten” – as in the Roman numeral X, meaning 10. But you may often hear it pronounced “Oh Es Eks” by people who are less impressed by old-timey numerals.) To add a bit of a twist, versions that were released between 2000 and 2011 actually had the proper name Mac OS X.

Name changes aside, though, they’re the same OS. Whether your version of the OS goes by macOS, OS X, or Mac OS X, they’re the same OS, made by Apple for the Mac computers noted above.

The exceptions, which probably don’t apply to you:

  • Old Apple computers (probably pre-2000): These may run an old OS called OS 9, OS 8, System 7, System 6, or other, mostly-forgotten names. (You won’t find many of those around any more, and it’s not likely that your computer uses one of these.)
  • Apple computers with the original macOS replaced by some other OS: This is very unlikely, unless you received your Apple computer from a serious computer hobbyist.

If you have a laptop computer called a Chromebook

This isn’t a common computer yet, but is becoming more common, especially in schools. If you use one of these machines, your OS is made by the company Google, and is called Chrome OS.

(The exception, as above: If your machine’s OS was replaced by a hobbyist with something else, then you have something else. It’s not likely.)

Bit Cafe isn’t focused on discussing Chrome OS right now; it could be, if readers ask for it!

If you have any other desktop or laptop computer

These include computers with hundreds of names, from dozens and dozens of companies including Dell, Sony, Toshiba, Asus, IBM, Lenovo, Acer, HP, Microsoft, and so many more.

If you have one of these machines, your OS is probably from the family of OSs called Windows, made by the company Microsoft. More specifically, the OS will likely be one of these Windows products: Windows 95, Windows 98, Windows 98, Windows ME, Windows XP, Windows Vista, Windows 7, Windows 8, or Windows 10.

(The exception, as above: If your machine’s OS was replaced by a hobbyist with something else, then your OS is that something else. It’s not likely – but if you received your computer from such a tech-lover, ask that person what the OS is. It might not be Windows.)

Bit Cafe isn’t focused on discussing Windows right now; it could be, if readers ask for it!

“OK, so now I know my OS. What version is it?”

If your OS is macOS (a.k.a. OS X or Mac OS X) from Apple, here’s how to check your version (or version number, as it’s often called):

Click the Apple menu. That’s the apple-shaped icon at the very top left corner of your computer’s screen.

  • A menu will appear. It will contain the words “About This Mac”. Click that.
  • A window will appear, displaying information about your Mac and its OS. That’s what you’re looking for!
  • When you’re done noting the information, you can click the red button in the “About This Mac” window to close it.

Details may vary by your version number, but your “About this Mac” window should look something like this:

About This Mac screenshot

From this – the small gray letters under the big “OS X” – you can see that this Mac is running the OS called OS X, and you can also see that the version number is 10.9.4.

If your version number is 10.10 or later, the “About this Mac” window will look more like this:


This window not only gives out the version number (10.10), but also the “code name” for this Version 10.10: “Yosemite”. (You might agree that a real word, like “Yosemite”, makes for a nicer name than “10.10”.)

Check your own version number now!

“OK, so now I know my version number. Anything else I should know about the version?”

Well, that version number is the key piece of information you need to know when seeking help for your questions. But as long as we’re here, let’s take a minute to become mini-experts in decoding that number, and also learn how to understand people when they talk about OS versions. This is actually simple stuff:

  • Read the version number like any decimal number (even if there are more decimals than it seems there should be): “10.9.4” is “ten point nine point four”. Likewise, “10.12” is “ten point twelve”.
  • A bigger number is a later version, i.e., a newer version. The above OS X 10.9.4, for example, was released (i.e., offered to the world) in June 2014. Apple released the version prior to that, 10.9.3, in May 2014.
  • Along with “later” and “earlier”, the words “higher” and “lower” are often used in referring to version numbers. For example, if the advertising for a new computer game says you need “OS X 10.8.1 or higher”, then the game should work if your computer is running OS X 10.8.2, 10.8.3, etc., or any OS X 10.9, or 10.10, etc. But it may not work if your computer is running the older OS X 10.8.0, or any OS X 10.7, or 10.6, etc.
  • All versions of macOS (a.k.a. OS X or Mac OS X) start with the number 10. Thus, in “10.9.4”, the “10” alone actually doesn’t tell us anything about what version of macOS we’re looking at; they’re all 10.something! We need to look at the second and third numerals (especially the second).
  • The second numeral in the version, i.e., the “9” in “10.9.4”, is a major version number. For example, 10.8 was the major version before 10.9. The next major version, released in October 2014, is 10.10 (yes, that’s “ten point ten”).
  • The third numeral in a version number,  i.e., the “4” in “10.9.4”, is a minor version number. The differences between minor versions are small – possibly not even noticeable.
  • Apple releases new major versions every year or two, and each release is something of a big deal, followed closely by customers and press. New major versions typically make several notable changes to the previous version (including adding new, heavily-advertised features), as well as many smaller, less noticeable changes. The difference between major versions can be pretty, well, major.
  • Apple releases new minor versions fairly frequently. These typically fix some small security issues or other minor problems; the differences between a new minor version and the previous minor version may be things you don’t even notice.
  • For the above reason, people using macOS typically just refer to the OS by its major version name: 10.9, 10.8, 10.7, and so on. I typically forget what the most recent minor version number is on any computer of mine (am I running 10.10.2? 10.10.3?), but I do know what my major version number is (as of this writing, it’s 10.14 for my main Mac laptop, but I also have a couple of outdated machines running the years-old 10.5). You should remember your major version number!
  • Just to make things a little more fun: People often refer to their OS by its code name – essentially a nickname – instead of version number. Long story short: When Apple started creating Mac OS X 10.0 many years ago, it used “Cheetah” as the code name for the new project. That was simply the name the project team used to refer to the product while creating it. The word got out, and people everywhere were talking about this new “Cheetah” that was under development. When the product finally came out in 2001, Apple announced its new “Mac OS X 10.0” – but people just kept calling it “Cheetah” instead. (And why not? “10.0” is boring; “Cheetah” is cool.) Since then, each new major version of OS X has had its own code name, and both users and Apple have come to use those names openly. (“Snow Leopard” is just tonier than “OS X 10.6”.)

To help you tell a “Tiger” from a “Puma” from a “Sierra”, here’s a guide to your major versions of macOS. Which one do you have on your Apple computer? Open the “About This Mac” window, check the version number, and find out!

Major version Code name Year released Price Notes
Mac OS X 10.0 Cheetah 2001 US $129 The first big public release of Mac OS X.
Mac OS X 10.1 Puma 2001 Free Released soon after 10.0 “Cheetah” to fix various problems.
Mac OS X 10.2 Jaguar 2002 US $129 Another major version.
Mac OS X 10.3 Panther 2003 US $129 Another major version.
Mac OS X 10.4 Tiger 2005 US $129 Another major version.
Mac OS X 10.5 Leopard 2007 US $129 Another major version.
Mac OS X 10.6 Snow Leopard 2009 US $29 Another major version (and a particularly popular one at that). New lower price, too!
Mac OS X 10.7 Lion 2011 US $29 Another major version.
OS X 10.8 Mountain Lion 2012 US $19 “Mac” was dropped from the OS name for simplicity.
OS X 10.9 Mavericks 2013 Free Named after a beach in California. And free!
OS X 10.10 Yosemite 2014 Free Another California place name.
OS X 10.11 El Capitan 2015 Free Named after a rock formation within Yosemite.
macOS 10.12 Sierra 2016 Free Another name change: It’s “macOS” from now on.
macOS 10.13 High Sierra 2017 Free Another major version. Still using California locations for the code names.
macOS 10.14 Mojave 2018 Free Another major version. Still using California locations for the code names.

“So, when I install software, it has to be software matched to my OS and version, right?”

Exactly. Since the OS is the “infrastructure” that lets apps run on your computer – the “liaison” between the apps and the actual computer machinery, in a way – the apps and your computer’s OS have to understand each other.

That means if your computer’s OS is macOS, you want apps that are made for macOS, not (for example) for the OS named Windows. And if your computer’s OS is some version of Windows, then you want apps that are made for Windows, not (for example) for macOS.

All right then. It makes sense that if you buy (for example) a game app, you need to make sure it’s the right one for your OS. But do you need to worry about your OS’s version number too? Quick answer:

Some apps aren’t too fussy about version numbers; if the app is made for macOS and your computer runs on macOS, then the app should work for you, regardless of how new or old your macOS version is. But other apps can be picky, typically because they depend on some newer OS features that are found only in newer versions of the OS. So, if the app requires (for example) OS X 10.6 or higher, but you your Mac uses the older OS X 10.5, then the app likely won’t work for you.

(Some apps may even get picky about the specific computer you have. Sometimes the reasons sound arcane: something technical-sounding about requiring a certain chip set or graphic processing unit in the computer. Other times, the reasons are very easy to understand: an app that takes surveillance videos, for example, may understandably require that your computer have a built-in camera.)

In short: When you buy or otherwise install apps (including free ones!), check the listed requirements in the advertising or other material, to make sure it’s the right software for your OS (and, in some cases, the right software for OS version and for your computer itself).

“Anything else I need to know?”

That’s more than enough for now! You know what operating system is on your computer, and you know its version. When you seek help with questions, you’ll have this very important piece of information.

In fact, this is one of those pieces of information you should write down! Put it down in your Tech Notes so it’s instantly ready when you need it.

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