History of Open Office
In 1999, StarOffice was acquired by Sun Microsystems; they released the source code online the next year as OpenOffice.org. At the same time, Sun continued to develop StarOffice; StarOffice was based on OpenOffice, but contains additional code not licensed under the GPL. The free, open source version is generally referred to as OpenOffice.org to distinguish it from other versions.
Open Office includes a word processor (Writer), a spreadsheet program (Calc), a presentation program (Impress), a drawing program (Draw), a database program (Base), and a formula generator (Math). Generally each program is compatible with the corresponding Microsoft Office program, so Writer can open and save Word files and Impress can do the same for Powerpoint files. It can also handle PDF documents, although importing them requires a free plugin.
Star Office / Oracle Open Office contains everything found in Open Office, as well as additional fonts and templates, a different spell checker and thesaurus, a clip art gallary, and other items. Naturally, this additional functionality comes at a cost; the software traditionally cost $70, but the price (for the personal edition) has now been lowered to $50.