Linux is basically a completely open source kernel which connects your hardware to applications(same as other OSes), it can be used freely and for lots of reasons, like Desktop mode for a daily usage, server mode to act as an FTP server, storage, web server, database, router, etc..., different versions of Linux are called distributions or in short distros, Linux is almost everywhere
here are some examples of Linux use cases:
Linux Focus is security and stability, it has different features to act as a firewall, it is immune to viruses(comparing to windows which you can not use if there is no anti-virus on it). stability of Linux is something that the world is benefiting from, we have Linux servers that have not been restarted for more than 12 years(the uptime is crazy in these systems), and if you are working on a project that Uptime is an important factor, Linux could be your answer
Another thing about Linux is that this OS is very light weight, you literally can go to your basement and find a computer that is twenty years old, take it out, install a Linux on it, and use it as an OS that is able to do lots of tasks for you, you can even host a website or use it as an FTP server.
Linux distributions are generally either Debian Based or RPM Based, here are some examples of different distros which you can choose based on your needs:
the most popular desktop distro which comes as a server mode too
another popular distro which is my favorite on the laptops, and works great with detecting hardware drivers
when I want to set a server and I am looking for a 'stable yet easy to work with', I definitely go with this one, it has the desktop version(like other distros) as well but not my favorite
as its name implies, Oracle Linux is a great distro when you want to work with an Oracle Database or you want to install one
Alright, guys, I think this is enough to for Linux introduction, in later post I will get into detail about some distributions and show you some tricks for having a better use out of Linux
Note that this post is for people who have no knowledge about Linux or just heard the name, this is not a technical post, the only purpose of this post is to introduce Linux to beginners and make them interested in giving it a try