Operating Systems
Linux
Linux (commonly pronounced /ˈlɪnəks/ in English; variants exist) is a generic term referring to Unix-like computer operating systems based on the Linux kernel. Their development is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed by anyone under the terms of the GNU GPL and other free licenses.
Website: http://www.linux.org
FreeBSD
FreeBSD is a Unix-like free operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through the 386BSD and 4.4BSD operating systems. It runs on Intel x86 family (IA-32) IBM PC compatible computers, DEC Alpha, Sun UltraSPARC, IA-64, AMD64, PowerPC, ARM and NEC PC-9801 architectures along with Microsoft's Xbox.[1] Support for other architectures is in varying stages of development. FreeBSD currently has more than 200 active developers[2] and thousands of contributors.
Website: http://www.freebsd.org/
OpenBSD
OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution (BSD), a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995. The project is widely known for the developers' insistence on open source code and quality documentation, uncompromising position on software licensing, and focus on security and code correctness. The project is coordinated from de Raadt's home in Calgary, Alberta, Canada. Its logo and mascot is a pufferfish named Puffy.
Website: http://www.openbsd.org/
NetBSD
NetBSD is a freely redistributable, open source version of the Unix-derivative Berkeley Software Distribution (BSD) computer operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. Noted for its portability and quality of design and implementation, it is often used in embedded systems and as a starting point for the porting of other operating systems to new computer architectures.
Website: http://www.netbsd.org/
FreeDOS
FreeDOS (formerly Free-DOS and PD-DOS) is an operating system for IBM PC compatible computers. FreeDOS is made up of many different, separate programs that act as "packages" to the overall FreeDOS Project.[1] As a member of the DOS family, it provides mainly disk access through its kernel, and partial memory management, but no default GUI (although OpenGEM is listed on the official FreeDOS website).
Website: http://sourceforge.net/projects/freedos/
ReactOS
ReactOS is a computer operating system intended to be binary compatible with application software and device drivers made for Microsoft Windows NT versions 5.x and up (Windows 2000 and its successors). It is claimed to be composed entirely of free software, by means of a complete clean room reverse engineering process, with an extensive on-going audit, being undertaken to protect against claims made by those outside the project.
Website: http://www.reactos.org/
Syllable
Syllable Desktop is an original, modern operating system design, in the tradition of the Amiga and BeOS, but built using many parts from the GNU project and Linux. It is designed and optimised for your desktop PC, making it exceptionally fast and responsive and easy to use. It is under development, so it is interesting and even exciting to try out, but you have to decide for yourself whether it fits your needs already. Syllable Desktop runs on industry-standard Personal Computers with a minimum of a Pentium compatible processor and 32 MB of memory. It can make a new computer extremely fast and an old computer usable again.
Website: http://www.syllable.org
Haiku
Haiku is an open source operating system currently in development designed from the ground up for desktop computing. Inspired by the Be Operating System, Haiku aims to provide users of all levels with a personal computing experience that is simple yet powerful, and void of any unnecessary complexities.
Website: http://www.haiku-os.org/