Free Microsoft Office alternatives
Most Solid Office Suite you can use at your home and work: LibreOffice, Apache OpenOffice and Google Docs.
LibreOffice
LibreOffice is a successor to OpenOffice.org (commonly known as OpenOffice), which in turn was based on StarOffice. Many years of development have gone into the software, and it has been used in its various incarnations by millions. Today, LibreOffice is by far the most active continuation of the OpenOffice.org codebase, with releases every six months and hundreds of contributors. Also, LibreOffice uses libraries from the Document Liberation Project, handing control back to content creators.
LibreOffice is a powerful office suite – its clean interface and feature-rich tools help you unleash your creativity and enhance your productivity.
LibreOffice includes Writer, Calc, Impress, Draw, Base, Math and Charts which compatible with Microsoft Word, Excel, PowerPoint etc. It's the most powerful Free and Open Source office suite on the market.
Download LibreOffice from the Official Website
Apache OpenOffice
Apache OpenOffice is the leading open-source office software suite for word processing, spreadsheets, presentations, graphics, databases and more. It is available in many languages and works on all common computers. It stores all your data in an international open standard format and can also read and write files from other common office software packages. It can be downloaded and used completely free of charge for any purpose.
Download from their official website
Google Docs
Best for cloud collaboration
Google Docs brings your documents to life with smart editing and styling tools to help you easily format text and paragraphs. Choose from hundreds of fonts, add links, images, and drawings. All for free.
Others
There are other alternatives such as SoftMaker FreeOffice, SSuite and WPS Office - 2016 version is most similar to Microsoft Word, but their latest version started to put watermark on the print or PDF exports, so no longer makes it a real free alternatives.
As for FreeOffice and SSuite, so far not as popular as LibreOffice and OpenOffice, so it's up to you to give it a try.