OpenOffice.org (OOo) (the ".org" inclusion is due to a trademark dispute) is an office applications suite. It is intended to be compatible with, and directly compete with, Microsoft Office. OOo is free software under the LGPL or SISSL and is available for Microsoft Windows, Unix-like systems, and Mac OS X.
OOo is based on the code from an older version of StarOffice that was acquired and made open-source by Sun Microsystems with the aim of breaking the market dominance of Microsoft Office and allowing Sun access to rapid development at reduced cost. It also allowed the general public a version of StarOffice that was free including the source code.
According to its Mission Statement, the OpenOffice.org project aims "To create, as a community, the leading international office suite that will run on all major platforms and provide access to all functionality and data through open-component based APIs and an XML-based file format."
The project aims to compete with Microsoft Office and emulate Microsoft Office's look and feel where suitable (the interface is similar to that of Microsoft Office XP). It also imports from and exports to almost all Microsoft Office file formats. The ability to read and write Microsoft Office file formats is an essential feature of OOo for many users.
The primary development platforms for OOo are Microsoft Windows, GNU/Linux, and Solaris, with ports available or in progress for OS/2 and many Unix-like operating systems. There is a version of OOo 1.1.2 for Mac OS X, which requires the use of X11.
OOo Version 1.1 includes:
- Writer (word processor)
- Calc (spreadsheet)
- Draw (graphics program)
- Impress (presentation program)
- Database User Tools
- Visual HTML editor
- Macro recorder
- StarOffice Basic
- Math (mathematical formula editor)
- Export and import Microsoft Word and DocBook XML, export PDF and Macromedia Flash.
OOo can, with some effort, be configured to integrate with databases such as MySQL and PostgreSQL, which offer similar functionality to Microsoft Access. OOo 1.1 also includes Quick Starter, a system tray application which occupies around 64MB of memory, but improves the launch time by preloading application libraries into memory in the background and then bringing up the user interface when launched.
OOo 1.0 was widely criticized for its performance and memory footprint compared with Office 97 or Office 2000. With OOo 1.1 both problems have been somewhat alleviated, but it remains notoriously large and slow  . Increasing performance and lowering memory footprint were both made priorities for OpenOffice.org 2.0 and pre-release versions show considerable improvements in both areas.
The suite is currently available in 25 different languages. Further translations by the development community are underway.
OOo has become a serious competitor to the dominant Microsoft Office application suite. Microsoft has publicly acknowledged OOo and denounced its usefulness — when an Israeli employment agency announced plans to switch from using Microsoft Office to OOo, an unnamed Microsoft representative was quoted as saying "The employment agency has selected an immature and unproven software package."  Microsoft has also published a competitive guide for its value-added reseller channel on how to market Microsoft Office over OOo   . Although Microsoft Office retains 95% of the general market, OOo and StarOffice have secured 14% of the large enterprise market  .
In August of 1999, Sun Microsystems purchased Marco Börries 's company StarDivision , which was then producing the commercial office suite known as StarOffice. Sun started giving away StarOffice 5.2 as a free download.
Build 638c — the first milestone release — was released in October 2001. OOo 1.0 was released on May 1, 2002 and OOo 1.1 on September 2, 2003. OOo 1.1.3 was released on October 4, 2004. The current stable release is version 1.1.4.
Development of OpenOffice.org version 2.0 is at an advanced stage. Milestone build 65 (a.k.a. 1.9.65, 1.9.m65) was released on December 15, 2004. The first Beta release is scheduled to be released in January, 2005, a release candidate in February followed by the final release in March.
Main article: StarOffice
Sun subsidises OOo development in order to produce the next version of StarOffice. Releases of StarOffice since StarOffice 6.0 have been based on the OOo codebase, with some proprietary components included:
- Certain fonts (especially Asian language fonts)
- Adabas D database
- Some templates
- Clip art gallery
- Some sorting functionality for Asian versions
- Some file filters.
The current version (early 2004) of StarOffice is 7.0.
As of 13:50, 1 Dec 2004 (UTC), the security site Secunia.com counts 2 security flaws unpatched (not yet fixed) for Microsoft Office, vs zero security flaws not yet fixed for OpenOffice.org.
The document file format used by OOo is based on XML and several export and import filters. All external formats read and written by OOo are converted back and forth from the internal XML representation. By using compression when saving the XML to disk, OOo's files are generally smaller than the equivalent binary Microsoft Office files. The OOo file format is also the basis of the OASIS Open Office XML file format standard.
The upcoming OOo version 2.0 has the following goals: better interoperability with Microsoft Office; better performance, with improved speed and lower memory usage; greater scripting capabilities; better integration, particularly with GNOME; an easier-to-find user-friendly database front end (OpenOffice Base) for database access with easy-to-use report, form and query creation wizards that allows users to access existing dBASE, Microsoft Access and MySQL databases, a new built-in SQL database, and improved usability.  Snapshots of development in progress are released every few weeks in the developers' zone of OpenOffice.org.
The OOo project is still essentially run by StarOffice staff, and getting non-Sun contributions into the core codebase is notoriously difficult, even for the project's other corporate sponsors. 
GNOME and KDE integration
Work is also in progress on better integration with KDE — Cuckooo (OOo as a KPart and hence fully integratable with KDE), KDE vclplug (using the Qt toolkit rather than OOo's own toolkit) and KDE NWF (Native Widget Framework, to give OOo the look of the host platform). This work was started by Jan Holesovsky and is currently sponsored by SuSE.
Recently, a version of OpenOffice.org was released with KDE-style icons and dialogue boxes, known as OpenOffice.org 1.1.3-kde  .
Mac OS X
A native Mac OS X port with an Aqua interface is being worked on, but will likely not be finished until 2006. The porting team is waiting on the OpenOffice 2.0 toolkit API being finalized before they can begin.
There is a scripting project which aims to be a repository for distributing macros.
OpenGroupware.org (OGo) is a set of OOo extension programs to share OOo files, calendars, address books, e-mails, instant messaging and blackboards, browse the web and access other groupware applications.
There is also an effort to create and share templates and other goodies at OOExtras  .
- OpenOffice.org , the project's homepage
OpenOffice.org for Developers
- StarOffice/OpenOffice.org "Q" Product Concept — OOo 2.0
- 2.0 snapshot builds
- KDE Integration Project
- Ximian's patches to OpenOffice.org (see also  )
- OpenOffice documentation wiki: FAQs and HowTos
- The OpenOffice documentation project
- OOExtras: Extras for OpenOffice.org
- OpenOffice OpenGroupware.org