It appears that not everyone who would post here knows what free softwareis. The terse group description "Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software.", though an excellent summary and reminder, isn't very useful to those who are new to the concept.
Free Software refers to software that is free in much the same way that a free market is free, or else free speech. More precisely, it is software that guarantees the following four freedoms:
The freedom to run the program, for any purpose (freedom 0).
The freedom to study how the program works, and adapt it to your needs† (freedom 1).
The freedom to redistribute copies so you can help your neighbor (freedom 2).
The freedom to improve the program, and release your improvements to the public, so that the whole community benefits† (freedom 3).
†Access to the source code is a precondition for this.
In order to help people distinguish Free Software from non-free software, this list may help some.
But really the key to free software is to recognise the spirit with which it is offerred. The most common two software licences, the GNU GPL and LGPL invoke a different kind of trade: I produce code, and I give it to you, with the source, on the condition that the source to any modifications that you make will the passed onto subsequent owners of the code on request, including quite possibly myself. Other free software licences do not make this transitivity condition, and the developers' motive is likely to be slightly or even somewhat different. Very frequently, software of low quality is vastly improved by the process of peer review, refinement, and extension that is facillitated by the approach of most free software licences.
Free software can also be produced by those, not wanting anything back for themselves, wish to change the socioeconomic landscape for coders, so that the software that is prevalent is increasingly software for which one can see how it works, experiment with, learn from... In general, it promotes a learning, creative environment, and (importantly) a free environment.
There is also an advantage to non-coders of free software, and that is that free-software is likely to have been audited by many good, and idealistic minds, so that you can be pretty sure that the software is of reasonable quality, and is free of malware. Also, you know that the coders, being motivated largely by high ideals, won't want to be fobbing you off with low quality shit, nor will they be saving the best ideas for the "paid version".
In some ways the term "free" in free software is misleading. In other languages, "costless" and "liberated" tend to be expressed by different words. Because of this confusions between different meanings of the word "free", it appears that this kind of clarification is needed far more often than it might otherwise be needed. I suppose that this is one reason why the term "open source" was coined.
Those interested in freeware should really be posting here!
Morosoph