Free Software is similar to Open Source. Users must be able to freely use, study, copy, redistribute, modify, and publish modified versions of the software. Here free means Freedom to use rather than Free in price (as in Freewares). Both Free and Open Source have similar objectives but differ on which term is better to covey these objectives.
Free Software Foundation (FSF) is a Non-Profit organization dedicated to promote development and usage of Free Software. To be considered Free Software, Software must meet Free Software definition as defined by FSF.
