Linux is a free and open-source operating system based on the Linux kernel. Operating systems based on Linux are known as Linux distros. Examples include Debian, Ubuntu, Fedora, CentOS, Gentoo, Arch Linux, Kali Linux(hacking, Also used as security testing tool), Baishakhi(Develod mainly in bangali language) and many others.

What is Linux distros?

Linux isn’t like Windows or Mac OS. Microsoft combines all the bits of Windows internally to produce each new release of Windows and distributes it as a single package.Linux works differently. The Linux operating system isn’t produced by a single organization. Different organizations and people work on different parts. There’s the Linux kernel (the core of the operating system)The Linux kernel has been under active development since 1991, and has proven to be extremely versatile and adaptable.the GNU shell utilities (the terminal interface and many of the commands you use), the X server (which produces a graphical desktop), the desktop environment (which runs on the X server to provide a graphical desktop), and more. System services, graphical programs, terminal commands – many are developed independently from another.Linux distributions do the hard work for you, taking all the code from the open-source projects and compiling it for you, combining it into a single operating system you can boot up and install. 

Popular Linux distributions are: 

• MX Linux
• raspberry pi
• Manjaro
• Linux Mint
• elementary
• Ubuntu
• Debian
• Solus
• Fedora
• openSUSE

What is the Linux kernel?

The kernel is a central component of an operating system that manages operations of the computer and hardware. It basically manages operations of memory and CPU time.The kernel is so named because—like a seed inside a hard shell—it exists within the OS and controls all the major functions of the hardware, whether it’s a phone, laptop, server, or any other kind of computer.

Kernels job in operating system

1.Memory management

2.Process management

3.System calls and security

4.Device drivers

Architecture of Linux:

What is Shell :

It is an interface among the kernel and user. It can afford the services of kernel. It can take commands through the user and runs the functions of the kernel. The shell is available in distinct types of OSes. These operating systems are categorized into two different types, which are the graphical shells.Shell is an environment in which we can run our commands, programs, and shell scripts.