It is compatible with all other major office suites and is free to download, use, and distribute. It was previously known as StarOffice before it became an open-source project. OpenOffice comes with OpenWriter - a word processor, OpenCalc - a spreadsheet and OpenImpress - a presentational package.

Compatible with other major office suites, OpenOffice.org is free to download, use, and distribute. Download it now, and get:
Writer
Writer – a word processor you can use for anything from writing a quick letter to producing an entire book.
Spreadsheet
Calc – a powerful spreadsheet with all the tools you need to calculate, analyse, and present your data in numerical reports or sizzling graphics.
Presentation
Impress – the fastest, most powerful way to create effective multimedia presentations.
Vector drawing tool
Draw – lets you produce everything from simple diagrams to dynamic 3D illustrations.
Database Base – lets you manipulate databases seamlessly. Create and modify tables, forms, queries, and reports, all from within OpenOffice.org
Mathematical function creator
Math – lets you create mathematical equations with a graphic user interface or by directly typing your formulas into the equation editor.