Open source is a concept often associated with Linux and free software.
Linux is an open source project, which means that its source code is available for anyone to see. That’s different from, say, Microsoft’s development model, which is closed source. Microsoft’s source code is not widely available, and if you’re granted access to it (if you are, for example, a partner), you have to sign a nondisclosure agreement. Linux is also free and licensed under the GPL.
Open source as a development practice has a lot of advantages over closed source. One of them is what is known as Linus’ Law: “Given enough eyeballs, all bugs are shallow.” If source code is open, everybody can see it, and thus errors have more chances of being detected and corrected in a timely fashion.
There are currently many open source projects that, although they run on top of other operating systems besides Linux, are mostly associated with it. Some examples can be found in Table.
Some years ago, the open source concept became more institutional and often collides with that of free software, at least in the heads of their leaders. In 1998, the Open Source Initiative (OSI) was founded with the aim of making this family of software more appealing to commercial organizations, which may be scared by the concept of software being free. The open source model of development, the founders thought, had its own merits, whether the software produced was free or not. OSI tries to sell the business
case for open source as a pragmatic solution, without the moral philosophy entanglement of free software.
But the two concepts are often linked, giving rise to the acronyms FOSS (“Free and Open Source Software”) and FLOSS (the “L” from libre, Spanish for “free”).