Upgrade OS
i have a MAC Air running Darwin 15.5.0 can this OS be upgraded? What version can I upgrade to?
Question marked as
When you say Darwin, are you referring to Mac OS X / macOS? Or to the actual Darwin operating system, which consisted of some of the core components of Mac OS X, but did not have higher-level frameworks or a Mac GUI?
https://en.wikipedia.org/wiki/Darwin_(operating_system)
If you are running the Mac operating system, and want to know the newest version of that which your MacBook Air will install, please tell us the full model name (including hardware model year / time of year) of your Mac.
You can find this in the About This Mac dialog in the Apple () menu. Please don't post the serial number - that isn't a good idea, and we don't need it.