Linux is available in many distributions, each one packaging the kernal with a different set of additional features and UI elements.Windows, which has traditionally dominated the desktop operating system industry, especially in business and office applications, also provides server operating systems.
This can be helpful, but isn’t absolutely required.
Many developers work locally on a Mac and then deploy to Linux servers.
Linux — Linux is a Unix-like family of Operating Systems based on the Linux kernal developed originally by Linus Torvalds.
It is based on Unix, but did not reuse any of the original closed-source code. This, along with its technical suitability, has made it extremely popular for use on server hardware and other “big metal” systems.
OSX is primarily used for desktop computing, and has not gained much traction on servers.