So this is probably a very basic and obvious question for most people, but my google-foo is failing me and it just seems something is going over my head. I've heard numerous people refer to having a 'dedicated linux box' as a central part of a developer's setup.

I have been doing web-dev programming for about a year and understand the benefits of programming on a Unix/Linux system. But I seem to be missing what role a 'dedicated linux box' plays in the development process.

I would assume that it is used as a server of some sort, but I am yet to run across any needs to have a computer dedicated to running a linux server. Am I just being nieve and mistaking the commonality of programmers preferring to work in linux for a tool used by developers? What do most developers use their 'dedicated linux box' for?