In open source the term "free" is often used, sometimes with a qualifier, "free as in beer" or "free as in speech". What is meant with these qualifications?
Free as in beer, is like getting something without payment. Getting food from the community fair (There's one in Toronto that gives free hamburgers to the community every year), something from friends, these are things that you receive without making a payment. You don't pay money.
Free as in speech relates to the Free Software Movement. To recognize this, we normally refer to it adding the French word libre, in order to help imply the freedom meaning. This is the reason as to why we have the acronym FLOSS (Free/Libre and Open Source Software). Libre means that you are unrestricted, like a bird in the skies, to do certain things. With libre software, you can fork the software, and take it. You're allowed to do so, you're libre.
This is a confusion that can be quite confusing. As both words denote the same thing. With people around, they generally take the meaning of "free as in food", rather than freedom. People specify what they mean with the expressions to help clarify and assure themselves that their message can come across reliably.
"Free" is ambiguous in English:
- A free beer is a beer that you don’t have to pay for (you get it for free).
- A free speech is a speech where you have the right to express your opinion (you are free).
To disambiguate the meaning of "free", you can refer to these concepts:
- free as in beer, if it’s about the price of zero (aka. gratis)
- free as in speech, if it’s about the freedom (aka. libre)
@Zizouz212 almost got the idea 100%. These ideas are not the same otherwise there would not be two phrases. The big difference with this concept can best be described from a great How-To Geek Article on the subject.
"Free as in beer" is when someone gifts to you the software at no cost. You are in no way expected to pay any fee for this or give anything in return. You also cannot see the source code or any of the elements that make it up. Sure you may know that it contains an ingredient (C++,Java), but you don't know exactly how it is put together to make this great software.
One community (joke / accepted practice) for this saying is if you really enjoy a software you (could / should / it's nice) to buy the developer a beer. Basically where this saying came from.
The "free as in speech" is pretty much right on, but is in association to actual open source. You can see and use any version of the code to improve and help yourself or the community.
So like I said they are different and do not mean pretty much the same thing.
It is not unheard of for both to be true at the same time.
This question is answered up front in the FSF's What is free software?, which starts out by using the often quoted "free beer" / "free speech" analogy. Quote:
“Free software” means software that respects users' freedom and community. Roughly, it means that the users have the freedom to run, copy, distribute, study, change and improve the software. Thus, “free software” is a matter of liberty, not price. To understand the concept, you should think of “free” as in “free speech,” not as in “free beer”. We sometimes call it “libre software” to show we do not mean it is gratis.
I think this quote answers the OP's question pretty well.
However, to make the meaning of "free software" crystal clear, the FSF goes on to list the "four essential freedoms" that characterizes free software:
- The freedom to run the program as you wish, for any purpose (freedom 0).
- The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
- The freedom to redistribute copies so you can help your neighbor (freedom 2).
- The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.
This is IMHO, a very good definition of "free software". In just four short bullet points, we are given all the information we need to decide whether something qualify as "free software" or not.
In contrast, software that is just available at zero cost (aka. "freeware") may not provide any of these freedoms.
Personally, I prefer the word "freedom" over "free speech", as the former better conveys the idea of lack of restrictions. This version is also used as the title for the biography of FSF's Richard M. Stallman by Sam Williams.