Originally written as a free Unix clone by Finnish programmer Linus Torvalds in 1992, it quickly grew a large and devoted developer base for its open architecture and low cost. It is maintained as free and open source software, meaning anyone can read the original source code, make changes or contributions, and (hopefully) donate their changes back to the project for future inclusion.
Linux is the basic "kernel", the part of the operating system that provides ways to handle the hardware. On top of this sits the "GNU" stack -- a set of programs developed by the Free Software Foundation that allow users to interact with the operating system at a very low level. Tools like `ls` (which lists files in a directory) are GNU programs that pull information from the linux kernel. A number of graphical user interfaces have been developed to provide simpler and more intuitive ways to operate the computer.
Many companies and organizations have developed their own "distributions" of GNU/Linux. These are installable packages of various software meant to provide end users with a complete operating computer in a style similar to Windows or Mac OS X. Most distributions also have ways to easily find, download, and install free and open source software packages to provide additional functions like word processing or video playing.
In conversation with everyone but the hardest of hardcore nerds, "linux" or "Linux" is usually fine to refer to the combination of the kernel, the GNU stack, graphical user interface, and even the distribution.
- Ubuntu is the current leader in linux distributions, having focused on ease of use for the end user. A number of variants based on Ubuntu exist: for netbooks specifically, to change window managers, or in a server-specific configuration.
- Fedora started as a project by Red Hat, an early and respected linux service company, to focus on providing the latest software in the linux world.
- OpenSuSE is a somewhat milquetoast distribution, allowing a wide range of software with an interest in stability.
- Linux Mint focuses on extreme ease-of-use and is second only to Ubuntu in market share.
- Puppy Linux is designed to be small and quick, operating from a USB stick and on older and more constrained hardware than other, more fully-featured distributions.
Unix was developed forty years ago at AT&T's Bell Labs as an operating system for early digital computers. It has since been rewritten, remixed, copied, and released countless times by many different companies and organizations, and it often finds a home on high-powered servers. Underneath its polished user interface, Mac OS X is built on Unix underpinnings. "Full" versions of Unix are usually designed for enterprise use, making them gratuitously overpowered for small community shops.
- OpenIndiana is a community fork of the OpenSolaris project originally started by Sun Microsystems and discontinued by Oracle. Primarily made for enterprise use, it is still under development and
- Berkeley Software Distribution (BSD) is a catch-all term for a copy of Unix made by students at the University of California in the 1980s. It has since evolved into three major distributions: the general purpose FreeBSD, the network-focused NetBSD, and the ultra-secure OpenBSD.
Replacements for proprietary software
Many free and open source replacements for proprietary software were originally built for GNU/Linux. In some cases, this may require downloading and installing Linux-based graphics layers (like X11) or operating environments (like Cygwin) in order to run them on Windows or Mac. If special software is required, it is usually made quite clear (and available) on the project's download page.
- OpenOffice.org - recently bought by Oracle and given to Apache after some controversy, this is the most common replacement for the Office suite and can read and write old and new Office file formats. Free, open source (LGPL), available for Linux, Mac, and Windows.
- LibreOffice - fork of OpenOffice.org made by the community after discomfort with Oracle, this is nearly identical to its predecessor. Free, open source (LGPL), available for Linux, Mac, and Windows.
- KOffice - Office replacement made specifically for the KDE window management system within Linux. Free, open source (GPL and LGPL), available for Linux with some preliminary support for Mac and Windows.
- AbiWord - Word processing program only. Free, open source (GPL), available for Linux and Windows. Mac development tends to lag.
- Gimp - raster/bitmap image editor, replacing Photoshop. Free, open source (GPL), available for Linux, Mac, and Windows.
- Inkscape - vector graphics editor, replacing Illustrator. Free, open source (GPL), available for Linux, Mac, and Windows.
- Scribus - desktop publishing application, replacing InDesign. Free, open source (GPL), available for Linux, Mac, and Windows.
- Kompozer - WYSIWYG web page design (HTML and CSS), replacing Dreamweaver. Free, open source (MPL, GPL, and LGPL), available for Linux, Mac, and Windows.
- Riseup.net is a radical tool that provides secure email accounts and email lists for activists and organizers.
- Resist.ca also provides secure email accounts and lists, except they're from Canada.
- Doodle makes little charts that you email out to a group to find a good meeting time. Everybody fills out their availability and you can easily see what time works best.
- CiviCRM is a flexible customer relationship management tool, and can be set up to track volunteer hours and customer visits.
- FreeHub is a web-based membership tracker developed by the San Francisco Bicycle Kitchen, available either hosted by SFBC or as a locally served site.
- Austin Yellow Bike Project has their own volunteer and membership tracker that may be available to other collectives.