OpenOffice.org (OO.o or OOo) is a free cross-platform office application suite available for a number of different computer operating systems. It supports the ISO standard OpenDocument Format (ODF) for data interchange as its default file format, as well as Microsoft Office formats among others.
OpenOffice.org was originally derived from 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; later versions of StarOffice are based upon OpenOffice.org with additional proprietary components.
The project and software are informally referred to as OpenOffice, but this term is a trademark held by another party, requiring the project to adopt OpenOffice.org as its formal name.