Below is the text from an introduction to free software handed out at the skill share.
Free Software and the foundations of GNU/Linux
Free Software Definition
Free software is defined as software that can be used, studied and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only to ensure that further recipients can also do these things. To make these acts possible, the human readable form of the program (called the source code) must be made available. This definition intends the word 'free' to mean “free as in free speech” and not “free as in free beer” with emphasis on the positive freedom to distribute rather than a negative freedom from cost. Free software is thus distinct from freeware which is proprietary software made available free of charge.
Alternative terms for free software have been coined in an attempt to make the use of “free” less ambiguous. The most common is “open-source software”. Free software is also known as “software libre”, “free, libre and open-source software” (“FLOSS”), and “free/open-source software” (“FOSS”).
History of Free Software
In the 50s, 60s, and 70s, it was normal for computer users to have the freedoms provided by free software. Software was commonly shared by individuals who used computers and by hardware manufacturers who were glad that people were making software that made their hardware useful. In the 70s and early 80s, the increasing complexity of software applications drove the industry to protect their investments through application of copyright law, and they began using technical measures such as only distributing binary copies to prevent computer users from being able to study and modify the software.
In 1983, Richard Stallman launched the GNU project after becoming frustrated with the effects of the change in culture of the computer industry and users. Software development for the GNU operating system began in January 1984, and the Free Software Foundation (FSF) was founded in October 1985. He introduced the free software definition, and “copyleft”, designed to ensure software freedom for all.
Free software is a huge international effort, producing software used by individuals, large organisations, and governmental administrations. Free software is very widely used in Internet server applications such as the Apache web server, MySQL database, and PHP scripting language. Completely free computing environments are available as large packages of basic system software such as the many Linux distributions and FreeBSD. Free software developers have also created free versions of almost all commonly used desktop applications such as web browsers, office productivity suites, and multimedia players.
The economic advantages of the free software model have been recognised by large corporations such as IBM, Red Hat, and Sun Microsystems. Many companies whose core business is not in the IT sector choose free software for their Internet information and sales sites, due to the lower initial capital investment and ability to freely customise the application packages. Also, some non-software industries are beginning to use techniques similar to those used in free software development for their research and development: scientists, for example, are looking towards more open developmental processes, and hardware such as microchips are beginning to be developed with specifications released under copyleft licenses (see the OpenCores project, for instance). Creative Commons and the free culture movement have also been largely influenced by the free software movement.
As mentioned above, software development for the GNU operating system began in January 1984. Its name is a recursive acronym for GNU's Not Unix, which was chosen because its design is Unix-like, but differs from Unix by being free software and not containing any Unix programming code.
By 1991 the GNU project as well developed but many low level elements including the kernel were not complete. The Linux kernel was first released to the public on 17 September 1991, for the Intel x86 PC architecture. The kernel was coupled with the system utilities and libraries from the GNU project to create a fully functional free operating system, which led to an alternate term, GNU/Linux. Today the name is commonly shortened to Linux which, according to its Linus Torvald, its creator, is pronounced LIN-UKS.
Linux is released under the GNU General Public License (GNU GPL or simply GPL). The GPL is an example of a strong copyleft licensing scheme which gives every person who receives a copy of a work permission to reproduce, adapt or distribute the work as long as any resulting copies or adaptations are also bound by the same copyleft licensing scheme.
Today Linux is used in numerous types of computer, from embedded systems such as mobile phones to supercomputers, and has secured a place in many internet server installations with the popular LAMP application stack.
There are many different flavours of Linux that you can install on your home PC. These are called Linux distributions, or more commonly “distros”. A distribution is a project that manages a collection of Linux-based software, and facilitates installation of a Linux operating system. Distributions are maintained by individuals, loose-knit teams, volunteer organisations, and commercial entities. They include system software and configuration as well as later package upgrades and installs. A distribution is responsible for the default configuration of installed Linux systems, system security, and more generally integration of the different software packages into a coherent whole. Some well known distributions are Debian, Ubuntu, Gentoo, openSUSE, Fedora, Knoppix.
Linux is largely driven by its developer and user communities. Some vendors develop and fund their distributions on a volunteer basis, Debian being a well-known example. Others maintain a community version of their commercial distributions, as Red Hat does with Fedora.
Although Linux is generally available free of charge, several large coroporations have established business models that involve selling, supporting and contributing to Linux and free software. These include Dell, IBM, HP, Sun Microsystems, Novell and Red Hat. The free software licenses on which Linux is based explicitly accommodate and encourage commercialisation; the relationship between Linux as a whole and individual members may be seen as symbiotic. One common business model of commercial suppliers is charging for support, especially for business users. A number of companies also offer a specialised business version of their distribution, which adds proprietary support packages and tools to administer higher numbers of installations or to simplify administrative tasks. Another business model is to give away the software in order to sell hardware.