Uses of Linux 

Linux is an operating system to run Pc website or any electrical device.

Following are the uses of Linux :
Web Serving:

Nearly 60% of all websites on the Internet are run using an Open Source program named "Apache." Most often, it's run on Linux. 

Linux web server is not easy to hack and it can easily bear any DDOS(Denial of Service Shutdown) attack as compared to windows server. 

Networking:

Linux is based on Unix, an operating system developed in the 1970s and which is still used heavily today, especially to run the Internet. Linux is used both to run parts of the Internet, as well as to run small and large networks in corporations, offices and homes.
Databases:
Since Linux is stable, secure and robust, it's perfect for storing huge databases of information.
Desktops:
People use Linux on our home and work computers, because of its stability and flexibility.Mostly programmers and  developers use Linux for their work.
Scientific Computing:
Many dozens (or even hundreds or thousands) of Linux systems can be clustered together to work on a single task (like weather forecasting, physics simulations, computer graphics rendering, etc). Most of super computers use Linux as a operating system because of its flexibility, ease in use  and due to its security.
Mobiles:
Android use Linux kernel and earns billions from it.Besides Android Tizan and Ubuntu touch are also based on Linux kernel.