Free software is a term coined and promoted by the GNU project and Free Software Foundation. It is used for open source software which allows users to freely look at the source of the software, modify it, distribute it, and use it without any restriction. Software available without any payment is not necessarily free software. According to the definition as presented by the Free Software Foundation, the word Free in “free software” implies the idea of freedom rather than not having a cost. If software is available to be downloaded without being paid for, but the user is not able to modify the source then it is not free software. It is important to note the distinction here. Freeware is software that you don’t have to pay for. Free software is software you are free to modify and use for your own purposes. Freeware does not necessarily have to be free software as the source code can still be protected.
Free Software can be released under different licenses for example GPL, Apache, BSD, etc., and WordPress is an example of open source software released under the GPL or General Public License. This allows developers and designers to create plugins and themes that extend the functionality of WordPress and make it the versatile platform that it is. According to the GPL the only restriction is that all modifications of WordPress are required to have the same license.