You already paid for it.

No, when I bought the computer it came with (thinks...) Snow Leopard? Dunno, it's a mid 2010 Mac, and my memory doesn't go back that far.

Over 4 years ago. Big deal. Early upgrades were cheap*, but IIRC Mavericks was free. 

* certainly compared to Windows, not compared to free-but-no-one-other-than-geeks-and-tightarses-want-to-use-it Linux

But you had to buy a Mac to get OS X. Not free.

I could still be using the original OS X. That wouldn't be free. But the (recent) upgrades have been.

You cannot run Linux on thin air. You have to buy/build a computer. Not free. It might be cheaper than a Mac, but that's the price you pay for a free OS.

And the thread started as Windows-is-now-free. If you haven't got a PC, you will still need to buy one to run Win10. But if you already have a PC you can upgrade to Win10 for free. Bit that's already the case for OS X.

That is all. Imma dun.

Still wrong. To be able to get the current free OS X upgrades you had to spend some money to get the original OS X you had by buying a Mac.

Obviously hardware to run it an OS isn't free, but Apple aren't giving away OS X for free, you have to buy a Mac.

Yeah but once you've bought the £20 rPi to run Linux or £2500 iMac to run OSX then it's free. So it's basically the same thing. Right?

There's free and then there's Free.

http://venturebeat.com/2015/03/19/microsoft-says-free-windows-10-upgrades-for-pirates-will-be-non-genuine-and-unsupported-stays-mum-on-security/

Well that's disappointing. Making Win10 free for everyone (including pirates) was one of the smartest things MS have done for a long time. This pretty much negates that entirely.

You're free to pirate windows!