This is a question I have from the first day I've heard about open source codes. We see new versions of Linux kernel once in a while, means that people are still working on it. Who are these developers and who pays them and why someone pays developer to develop something free?
closed as too broad by Thomas Dickey, andcoz, Jakuje, jasonwryan, Wildcard Feb 29 '16 at 22:29
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It depends on what code you're talking about. The difference between most proprietary software and FOSS is that FOSS is developed by stakeholders rather than a single proprietor. Hardware companies want to sell more hardware so they contribute code to help make Linux work on their products to increase the value for the consumer.
Administrative stuff can be developed out in the community (like the initial versions of OpenStack were, and how cgroups came out of google) or it can be created by companies that sell consultation, training, and support (such as with Docker, most databases, most commercial distros, etc).
There are also the odd random contributions by government agencies, academic researchers, and what have you. Along with just random people who know how to code and want to be able to say they contributed something to a successful project.
Appliance vendors seem like they would want to contribute upstream but I don't know if that's actually common practice. It would be interesting to see what companies like F5 and Citrix would develop.
The nonprofit behind the Linux kernel even publishes a detailed report of who contributes and how much.
Sometimes, and only sometimes, not everything is about the money. Most of these developers have daytime jobs. As the previous poster said, some of these people, work for the companies, who benefit from improved Linux operations, by selling more hardware and software running Linux. Those companies, actively seek and employ people who can improve/develop code.
And some people do it because they like a good challenge. After all, Linux is created because Linus Torvalds was sick of proprietary, closed source, UNIX variant operating systems. I don't think he imagined his brain child becoming some behemoth like it is today, at the time he stared writing the code.
Exposure perhaps. Aids in building a profile?