I know Linux is an operating system but I see memes and posts about people arguing whether UNIX is an operating system or a kernel and stuff like that. So what separates the two? And what exactly is a kernel?
In: Technology
The kernel and the operating system are both somewhat vague terms, there’s no hard and fast exact meaning. It’s sort of like the difference between a town and a city – there are some people that will give you very specific and precise definitions, and also other people that will give you a mutually exclusive other specific and precise definition.
But broadly:
An kernel is the software the organizes all the hardware and provides a single platform for everything on else on the computer to work with so other software can all work together. You might have a web browser connecting to websites, simultaneously steam is downloading a game, also you’re playing some online game that’s also reaching out to the internet. The kernel is what figures out how to get all these things coordinated so all the programs get time on the CPU to actually execute, none of them are using RAM the others are using at the same time, and they can all share one radio antenna that’s doing the wifi signalling.
An operating system includes a kernel, and usually a lot of extra things too and it’s the baseline software meant for making the system actually usable to humans. For example: the MacOS operating system includes a whole graphical desktop environment, it includes Finder, and a lot of other things. The MacOS graphical desktop isn’t in the kernel – the kernel is just for managing the hardware and coordinating things between it – but it is software bundle with the system meant to enable a human user to actually use the thing.
UNIX was an operating system made at Bell Labs decades ago, but today UNIX is more of a “flavour” for other operating systems. Basically: UNIX was so popular a load of people copied it, and the original UNIX is basically dead, so today “UNIX” just means an operating system that fully embraces a lot of how UNIX originally worked. Often it means a system is [POSIX](https://en.wikipedia.org/wiki/POSIX) compliant – POSIX was basically an effort to make an official standard based off of UNIX so that all these many operating systems that were aping UNIX could all agree on some baseline features so that software written for one UNIX-flavour OS can generally work on any other.
Linux is technically not an operating system, it’s just a kernel. It’s routinely bundled with other software like [the GNU toolchain](https://en.wikipedia.org/wiki/GNU_toolchain) in to so called “Linux distributions” that are a full-fledged operating system.
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