LibreOffice is an open-source personal productivity suite that gives you six feature rich applications for all your document production and data processing needs, writer, calc, impress, draw, math, and base. Support and documentation is free. LibreOffice also comes configured with a PDF file creator, meaning you can distribute documents that you're sure can be opened and read by users of almost any computing device or operating system. (FreeWare) Website: http://www.libreoffice.org/
Open Office and Libre Office were originally the same, but now there may be some differences.