OpenOffice.org is a free office suite of applications available for many different operating systems including Linux, Microsoft Windows, Solaris and Mac OS X. It supports the OpenDocument standard for data interchange.

OpenOffice.org is based on StarOffice, an office suite developed by StarDivision and acquired by Sun Microsystems in August 1999. The source code of the suite was released in July 2000 with the aim of reducing the dominant market share of Microsoft Office by providing a free, open and high-quality alternative. OpenOffice.org is free software, available under the GNU Lesser General Public License (LGPL).

The project and software are informally referred to as "OpenOffice", but project organizers report that this term is a trademark held by another party, requiring them to adopt "OpenOffice.org" as its formal name, and abbreviated as OOo or OO.o.

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