Open source software is software distributed with its source code and allows users to modify and redistribute the software. Examples of popular open source software include the Linux operating system, Apache web server, and programming languages like Perl and Python. The open source software development model is collaborative and based on the idea that "given enough eyeballs, all bugs are shallow." Open source licenses like the GNU General Public License allow users freedom to use, modify and distribute software. Creative Commons licenses provide similar flexible copyright options for non-software works.