Linux and UNIX kernel and how they are related to Windows, Mac OS, Ubuntu, etc...

First, let's see how operating systems are working with hardware. there are several things components with operating systems to work.

1. Hardware — physical hardware in a computer.
2. Kernel — It is the core of an operating system. It manages hardware-level kinds of stuff. CPU, ram devices, etc.
3. Shell — The computer program that we can interact with hardware through the kernel. this is a command line-based one.
4. Terminals — These are the program that we can use with shells. we can load a shell into the terminal and work with it.
5. Applications — Utility programs we can use for our day-to-day work with OS.

2nd part Kernels.

Unix.

Unix is an OS which is created at Bell Labs (AT&T) in the early 1970s by Ken Thompson. at first, it was called UNICS.
Later after some versions, this was used by some universities. University of California at Berkeley releases the Berkeley version of Unix.
Berkeley Software Distribution(BSD). There are some new features with the BSD version of Unix. Virtual Memory model, BSD sockets (think TCP/IP), vi editor, CSH (the first shell designed for interactive use).
AT&T and BSD code bases were pulled into “Official UNIX” and these were released in UNIX system V release 4 (SVR4). This was a successful one at that time. Bourne shell was used with Unix version 7.
UNIX kernel used for SunOS, Solaris, HP/UX, etc.

Linux

Linux is a kernel written by Linus Torvalds in 1991.it is like a clone of Unix.
but all written from scratch.
In 1983, Richard Stallman started the GNU (GNU is not Unix)project to create a Unix-like OS. Also by the early 1990s, he wrote a GNU General Public License (GPL).
Linus used this for Linux OS to make it open source.
in 1996 Linus intrudes on The Tux (a penguin) official mascot of Linux.
bash (Bourne again shell) This was used in Linux as a free enhanced version shell.

This is a picture of the evaluation of kernels.

Evaluation of kernels

So, basically, Linux is just a kernel. it is maintained by Linux Foundation.
Linux kernel is the most distributed kernel on earth.
others can use this kernel to make operating systems.

For more info about kernel types click here.

3rd part OS

1. Linux Operating Systems.

There are lots of Linux-based distributions. They are all based on the Linux kernel. Ubuntu, Redhat Kali, etc.

bash is the default shell and there are lots of customs shells also.
Linux has terminal programs to use with shells. that we can use for scripting and other tasks.

2. Mac OS

Mac OS is using XNU kernel which is developed by Apple in 1996.
it is based on the Unix kernel.
mac os has bash and Zsh shells. defualt shell is Zsh.

3. Windows OS

Windows has its own kernel Windows NT(new technology).
It has Powershell as a shell.
windows also have a Command shell which was used in early windows os.
Command prompt is the command line interpreter program that we can use with the command shell.

For more info:
Unix Vs Linux: What is the Difference Between UNIX and Linux (softwaretestinghelp.com)