<P> Proprietary software generally creates greater commercial activity over free software, especially in regard to market revenues . </P> <P> Examples of proprietary software include Microsoft Windows, Adobe Flash Player, PS3 OS, iTunes, Adobe Photoshop, Google Earth, macOS (formerly Mac OS X and OS X), Skype, WinRAR, Oracle's version of Java and some versions of Unix . </P> <P> Software distributions considered as proprietary may in fact incorporate a "mixed source" model including both free and non-free software in the same distribution . Most if not all so - called proprietary UNIX distributions are mixed source software, bundling open - source components like BIND, Sendmail, X Window System, DHCP, and others along with a purely proprietary kernel and system utilities . </P> <P> Some free software packages are also simultaneously available under proprietary terms . Examples include MySQL, Sendmail and ssh . The original copyright holders for a work of free software, even copyleft free software, can use dual - licensing to allow themselves or others to redistribute proprietary versions . Non-copyleft free software (i.e. software distributed under a permissive free software license or released to the public domain) allows anyone to make proprietary redistributions . Free software that depends on proprietary software is considered "trapped" by the Free Software Foundation . This includes software written only for Microsoft Windows, or software that could only run on Java, before it became free software . </P>

Who has access to the source code of proprietary software