Linux is an OS, which is not that popular for desktop machines, but is one of the most popular OSs for web servers. It is totally free, so you won't have to pay any license costs as part of your website hosting payments. Linux is also thought of as the most reliable Operating System these days and due to the permissions which files have as well as the file types that can be run, virus files that may infect a normal PC shall simply not be executed on a Linux-based server. Additionally, the OS is free, so it can be customized with no restrictions, as a way to meet the needs of the website hosting provider and their clients. This also means that unnecessary software packages can easily be removed to make the Operating system lighter and quicker, that can directly result in a lot better server performance. A lot of Linux machines have the Apache web server set up on them, since this program is also totally free, quick and stable. It's the most widely used web server out there and is part of the LAMP bundle that a lot of script applications, like WordPress and Joomla™, require. LAMP is an abbreviation for Linux, Apache, MySQL and PHP.
Stable Linux with Apache in Shared Hosting