As you know Microsoft office is most popular for writing documents, spreadsheets, databases and for using it with your email service. You can write documents in .doc .txt and some other popular formats using Microsoft Office Word. If you want to make presentations then you can use PowerPoint. It is very useful and is essential for everyone but it is not free. There are some other freeware alternatives that give you services like Microsoft office without any cost. You can get too much freealternative software for Microsoft Office but I am going to tell you about some popular alternatives.
Apache OpenOffice is one of most popular free alternative to Microsoft Office. It is suitable for word processing, spreadsheets, presentations, graphics, databases and much more. You can get third party extensions for some more features. Its best thing is that it is free for any purpose; you can request new features and report bugs. I used this so I recommend this.
Another good free alternative to Microsoft Office is LibreOffice. It can be used for text documents, drawing, spreadsheets, databases, presentations and some others. It is available with +30 languages. You can use it on Microsoft Windows, Mac OS X and some others (Debian, Fedora, Ubuntu etc). Just download install and start using it. It is stable because it is free for almost 20 years. If you previously used Microsoft Office then you don’t have to worry due its similar look and feel to Microsoft Office.