This page has links about different operating systems.
DistroWatch.com (distrowatch.com) DistroWatch follows the development and distribution of Linux operating systems.
Debian (www.debian.org) Debian is a free Linux based operating system popular on personal and network computers.
Red Hat (www.redhat.com) Red Hat is a leading open source developer and designers of Red Hat Enterprise Linux.
openSUSE (www.opensuse.org) openSUSE is a Linux distribution supported by the German based openSUSE Project.
Apple OSX (apple.com) Apple develops the proprietary Apple OSX used on a variety devices including ipads and phones.
Microsoft (microsoft.com) Microsoft developed the Window operating system which is popular on personal computers, servers and the surface tablet.
Linux.org (www.linux.org) Linux is a popular UNIX like operating system popular on personal computers and servers.
Kernel.org (www.kernel.org) Kernal.org has archives of the Linux Kernal.
UNIX (www.unix.org) UNIX system is an open source UNIX-like operating system that was first developed by Bell Laboratories and later became the base for popular branches of operating system development.
FreeBSD (www.freebsd.org) Free BSD is an operating system based on the Berkeley Software Distribution of UNIX.
Ubuntu (www.ubuntu.com) Ubuntu is a popular (easy to use) Linux distribution based on the Debian. Ubuntu is South African for "unable to install Debian."
OpenBSD (www.openbsd.org) OpenBSD is by a committed open source branch of the BSD distribution.
CentOS Project (www.centos.org) CentOS is a community based fork of Linux.