UNIX was one of the first operating systems to be written in a high-level programming language, namely C. This meant that it could be installed on virtually any computer for which a C compiler existed. This natural portability combined with its low price made it a popular choice among universities. (It was inexpensive because antitrust regulations prohibited Bell Labs from marketing it as a full-scale product.)

Bell Labs distributed the operating system in its source language form, so anyone who obtained a copy could modify and customize it for his own purposes. By the end of the 1970s, dozens of different versions of UNIX were running at various sites.

After its breakup in 1982, AT&T began to market UNIX in earnest. It also began the long and difficult process of defining a standard version of UNIX.

Due to its portability, flexibility, and power, UNIX has become a leading operating system for workstations. Historically, it has been less popular in the personal computer market.

Today, the trademarked "Unix" and the "Single UNIX Specification" interface are owned by The Open Group. An operating system that is certified by The Open Group to use the UNIX trademark conforms to the Single UNIX Specification.

According to The Open Group's Web site, "As the owner of the UNIX trademark, The Open Group has separated the UNIX trademark from any actual code stream itself, thus allowing multiple implementations. Since the introduction of the Single UNIX Specification, there has been a single, open, consensus specification that defines the requirements for a conformant UNIX system. There is also a mark, or brand, that is used to identify those products that have been certified as conforming to the Single UNIX Specification, initially UNIX 93, followed subsequently by UNIX 95, UNIX 98 and now UNIX 03. Both the specification and the UNIX trade mark are managed and held in trust for the industry by The Open Group."

Daily Solaris News and Resources 
The site features the latest headline news affecting Solaris users and administrators. The resources cover a range of FAQ issues, along with security bulletins. It is a daily read for a Solaris Admin.

internet.com's Linux/Open Source Channel 
A comprehensive channel for links to Web sites for open source developers and users, from the beginner to the seasoned expert.

Unix Guru Universe 
Comprehensive site with resources for the 50+ flavors of UNIX, as well as specific links for system administration, networking, security, software, and newsgroups and help for user questions. The site also includes conference, vendor, and career information.

UNIX IT Toolbox 
Geared towards Unix professionals and users of Unix products. Offers forums for technical discussion, an integrated directory, white papers and daily news geared towards Unix professionals and users of Unix products. The portal also provides content, community, job postings and much more.

UNIX System Administration: A Survival Course 
This tutorial provides information on UNIX systems administration common tasks, frequently asked questions, useful tools , and many resources.

Independent study course in UNIX system administration
Offers information on a project that provides an independent study course in UNIX system administration. Contains links to a series of topics that describe general areas of UNIX system administration, a glossary, and reference library.

UNIX for Macintosh
Includes information on NetBSD/mac68k (BSD being another form of UNIX). The latest release is can be downloaded from this page.

UNIX help for users
Contains links to sections of a UNIX user help document. The sections include: tasks, commands, concepts, and utilities.

UNIX Research Central
Good collection of links to UNIX FAQs, documentation, tutorials, publications, and source executables and FTP sites.

UNIX system administration tools
Contains links to resources for UNIX and Solaris system administration, newsgroups, maintenance tools, network administration, user and X applications.

Unix: The Next Generation
Information Week feature article (May 1998) describing a surge in the UNIX market and attributes it to Intel's impending 64 bit processors.

UnixWorld
Online magazine with practical, tutorial-related articles and columns for beginners, programmers, and system administrators.

Yahoo!'s archiving and compression utilities for UNIX page
Yahoo!'s directory of links to shareware, resources, and utilities for data archiving and compression for UNIX systems.

Yahoo!'s UNIX page
Yahoo!'s directory of UNIX links.

Yahoo!'s UNIX page
Yahoo!'s directory of UNIX operating systems links.

Yahoo!'s UNIX user group page
Yahoo!'s directory of UNIX user groups.

Bugtraq Archives
Searchable archive of the UNIX security mailing list.

Homepage of the Open Source Initiative
The latest OSI news, an index of licenses with definitions, open source links, translations of the Open Source Definition and the history of the OSI and its board of directors.

The Open Group
Home page of the industry standards organization that owns the Unix trademark.

UNIX FAQ
This page links to several UNIX FAQs from the comp.unix.questions and comp.unix.shell newsgroups.