Freedom: as in Speech (libre) and as in Beer (gratis)
Most English-speaking people would think the term free software means that you can have a copy of it at no cost. Some people call it "Free as in beer". But this is not the kind of "free" that the meant.
That other kind of "free" has been called "Free as in speech". This one means that you have the freedom to inspect the source code for the software, modify it, and use or distribute your modified version.
Spanish makes it much easier, because the terms gratis and libre are much closer to these meanings of "free".
There is a lot of software that is free as in beer (gratis) but not free as in speech (libre). Examples are the Adobe Acrobat Reader, the Dreamweaver Flash Player, and many drivers or other software distributed with hardware.
It is harder to find software that is free as in speech (libre) but not free of cost, but such software does exist.
The term open source software was coined to try to combine these concepts, and also to possibly sound more attractive to business people, governments, and corporations. To make it even clearer, we often use free and open source software (FOSS) or free/libre open source software (FLOSS). This makes it clear that you can use and distribute the software without cost for the software itself, and that you can inspect the source code, modifiy it, and distribute the modified version.
GNU Public License (CopyLeft)
There are many kinds of licenses for software. The most "free", in a sense, is public domain, or no license at all. The problem with the public domain for software is that someone could take it and publish it, claim it is their copyright, and essentially steal it from the public domain. Or, more likely, they can take part of it, incorporate it into their proprietary software, and steal it that way.
Copyright is the process of claiming a monopoly on a certain expression of an idea or information. In theory, it is supposed to be for a limited time, but copyright durations keep getting extended, so copyrights now last nearly a century.
A copyright owner can set the conditions under which you can legally make copies of the copyrighted material. So most open source software is copyrighted by someone who restricts its use in a very special way. The software user may make copies and even change the program, as long as the resulting copies are each restricted to the same license.
This means that you are free to do what you will with the software, except that you cannot restrict others' rights to do the same. This has been called CopyLeft to indicate that the practical result is opposite from most copyright licenses.
There are many CopyLeft type licenses for open source software. We chose the GNU General Public License (GPL) because it is the best known open source license, and because we did not see any good reason to use a different one.
Freedom to Adopt or Fork
Some people think that commercial, proprietary software is better because you have the resources of a large company, like Microsoft, to support the product. What happens when that large company decides to retire that software? Occasionally a company will release the source code for that software so someone else can continue it, but that is very rare. Usually it is just orphaned.
With open source software, if the original author or developers decide they no longer want to support the project, someone else can simply take it over. There is no guarantee anyone will, of course, but the better the program was, the more likely that capable programmers will adopt it.
In fact, if the original author becomes somewhat dictatorial, and there are some developers who think the program should take a different direction, they can simply fork the program, meaning that they take the source code, give it a different name, and start modifying it to suit their needs. Now there will be two programs that will grow in different directions. The more popular one may continue, or if they meet different needs, maybe they both will be popular.
Besides software, data can benefit from open source philosophy. Proprietary
file formats are not in the customers' interests. For example, competing office
suites like OpenOffice.org, must reverse-engineer Microsoft Office’s
.xls word processor and spreadsheet formats to give you access to your own
letters, reports, and spreadsheets.
Since these formats are proprietary, Microsoft could declare that they are subject to the Digital Millennium Copyright Act (DMCA), and make it illegal for anyone to produce a program what would convert your own data to another format. They could also assert that their software patents apply, and anyone who uses the format must pay Microsoft for use of the patent.
With open formats, the details of the format are published to make it easy for anybody to produce compatible programs. Markus supports open formats such as CSV files. It may later support reading and writing Open Data Format (ODF) files directly. This will make it easy to transfer data to and from OpenOffice.org and other software that supports the ODF formats.
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