Ubuntu is a really popular OS, which employs the Linux kernel. Although it is used mainly on PCs, its server version has been gaining in popularity recently as well. Ubuntu is among the lightest Linux distributions out there and it's compatible with almost any kind of hardware, that makes it a universal OS. It's also very stable and secure and has an at least a 5-year support life cycle, so you can get official security and performance updates. Unlike various other Operating Systems, Ubuntu is distributed without any license fees and you're able to customize its core, and all of the countless packages it contains, in any way you find fit. This allows you to set up the proper software environment for all your web applications whatever their specifications. Because of the popularity of the OS, Ubuntu has vast developer and user communities, which means that you'll always find find plenty of materials online related to any question or problem which you may have.