Open-source software

On the previous page we learned about the origin of the Free Software Foundation (FSF) and the General Public License (GPL). Richard Stallman basically used copyright law against its traditional goal. Instead of protecting against unwanted copying, the GPL enforces that the software (and its source code) must forever remain free, which in this context means the right to use, copy, distribute, study, change and improve the software. To quote Richard Stallman it is “free as in speech, not as in beer.” The novel part of writing this idea down in the form of a license is that you can attach it to a piece of software and then actually sue someone who uses it (as is or in a modified form) and attempts to restrict these freedoms. Stallman and kindred spirits see free software as a social process: improving the world by distributing free software.

Another notable group that was founded a few years later is the Open Source Initiative (OSI). One of the best-known founders is Eric Raymond. They promote awareness of and advocate the importance of non-proprietary software. Their definition of “open source” is what is most often meant by the term. Their ideology differs a bit from Stallman. They are OK with both GPL-like licenses (that stipulate that redistribution and derivative works must be released under the same license) and permissive licenses (where derivative works can be released under any license).

Notable open-source licenses include:

• GPL (General Public License) which was already mentioned. The GNU utilities and Linux kernel are examples of software that is distributed under this license. GPL requires that software in which GPL software is used (derivate works) must itself also be released under the GPL license (which includes having to publish the source code).

• LGPL (Lesser General Public License): A lighter variant that does not require that derivate works must also get the LPGL license. It only requires that changes to the LGPL part are released. It was originally intended for software libraries, because they are used by a lot of other software.

• BSD family of licenses: These only require that the BSD license notice is retained when the software is used in another product. All forms of reuse and distribution are permitted. It does not require releasing the source code of derivative works. The FreeBSD and OpenBSD operating systems carry this license.

• MIT license: This one is similar. The original license note must be retained including a statement disclaiming all liability of the author for damages of any kind.

These are some examples of open-source programs that are historically notable and/or widely used.

• Apache: A web server that played a key role in the initial growth of the web. It is still used to serve many of the websites today, including this one.
• Sendmail: An e-mail server that is historically notable. It was used on the majority of web hosts. In recent times its use has declined dramatically. Postfix and exim, which are also also open source, are still widely used.
• Samba: Allows file sharing with Windows machines. It implements the SMB protocol that Windows uses for that.
• Git: A version control system for source code, originally created by Linus Torvalds. It is very popular and much more modern than old-fashioned version control systems like SVN.
• Notepad++: A nice text editor with tabs for Windows.
• LibreOffice: Office productivity software similar to Microsoft Office. It supports Microsoft Office files.
• LaTeX: Software to typeset documents. The input is text files with commands and the latex software can convert that to a PDF. It works brilliantly for writing mathematical and scientific books and papers and it is primarily used in those environments.
• GIMP: Image editor similar to Photoshop.
• Paint.NET: A simple image editor, only available for Windows. I use it for everyday tasks.
• Inkscape: SVG (vector graphics) editor.
• VLC media player: Can play any media file you throw at it. Is also available for Android TV.
• Firefox: A notable web browser. It was used by as much as 1/3 of people browsing the internet around 2010. Its use has declined since then though.
• Wordpress and other tools for web development