Open Office is a free office suit intended to replace Microsoft Office. It is distributed free of charge via download and is available for most popular operating systems. The GPL license under which Open Office is distributed allows unlimited use of the software for both home and business use. Although it can read and write Microsoft's proprietary document formats, Open Office defaults to the Open Document format.

Like Microsoft Office, Open Office is divided into a word processor, a spreadsheet application, a presentation manager, and a database application. In addition, there is a vector-graphics program and a mathematical formula editor. While previous versions of Open Office have been criticized for their unfamiliar layout, version OOo 2 has been designed to mimic Microsoft Offices' familiar interface. This change allows experienced MS Office users to feel right at home using Open Office.

Open Office began life as Star Office. When Sun purchased Star Office they split the development between their proprietary version of the software and the open source Open Office. As such, Open Office shares many of Star Offices' features, such as spell check, wizards, and macro support. In addition, any vendor that supports Star Office can also support Open Office.