And me from Sweden
LibreOffice is so good, you'll wonder why you ever paid for office software. It's compatible with all Microsoft document formats, and has almost every feature you'll find in the latest versions of Word, PowerPoint and Excel.
The suite contains six programs to cover every common office task: Writer, Calc, Impress, Draw, Math and Base. The last three are tools you won't find in many other free office suites, and are designed for vector diagrams, mathematical functions and databases, respectively. The latter is particularly useful; free alternatives to Microsoft Access are hard to find.
LibreOffice is an open source project maintained by a huge and enthusiastic community of volunteers constantly working to improve stability and add new features. There's a great selection of extensions and templates to make it even more flexible, and it's free for businesses as well as home users.
LibreOffice is a fork of Apache OpenOffice, and the two are extremely similar, but we’d opt for LibreOffice thanks to its more frequent update schedule and more modern interface.
LibreOffice is available for Windows, Mac and Linux, but there are no official mobile versions available except for a document viewer for Android.