The Open Source Initiative (OSI)
The OSI was created in 1998 by Eric Raymond and Bruce Perens, since they did not agree to the restrictions imposed by Stallman’s ideology of free (“free” as in freedom) software. While Stallman’s GPL required that every application bundled with a GPL software be GPL-ed, the OSI felt this would decrease the practicality of the product. The OSI allowed a more liberal form of licensing called the OSL or Open Source License, which assuaged the fears that proprietary software vendors had with the GPL. This allowed a hybrid mix of open source and closed source software to power most present GNU/Linux distros. Needless to say, that move has greatly increased the spread of the OS.
For example, the original GNU/Linux OS was text-based and worked off the command line. To be able to add a GUI to the OS it was necessary to include a windowing system. Such a system, called X Windows (or X11) was being developed by an organisation called the X Consortium. Being a closed source program, it was not possible to use it under the GPL. But being more liberal, the OSI license allowed the usage of the X Windows program with the other GPL programs in the GNU/Linux package. The direct result has been the greater acceptability of GNU/Linux on the Desktop, since most distros came bundled with a GUI. This has greatly contributed to the popularity of GNU/Linux among non-commercial users. While the original X11 was closed source, it was later on made open source and renamed Xfree86.