LibreOffice
LibreOffice is an office suite from a German non-profit, “The Document Foundation”. The suite has application for word processing (Writer), spreadsheets (Calc), presentations (Impress), vector graphics (Draw), database management (Base) and formula editing (Math). LibreOffice mainly uses the OpenDocument format to store files, but can also read and write the file format from Microsoft Office.
LibreOffice is licensed under the MPLv2.0 (Mozilla Public License) which is a copy-left license.