How is "open source" related to "free software"?
 
The Open Source Initiative is a marketing program for free software. It's a pitch for "free software" on solid pragmatic grounds rather than ideological tub-thumping. The winning substance has not changed, the losing attitude and symbolism have. See the discussion of marketing for hackers for more.
 
So that it is clear what kind of software we are talking about, we publish standards for open-source licenses. We have created a certification mark, "OSI Certified," to be applied only to software that is distributed under an open-source license that meets criteria set by the Open Source Initiative as representatives of the open software community. We intend this mark to become a widely recognized and valued symbol, clearly indicating that software does, in fact, have the properties that the community has associated with the descriptive term `open source'.