Like much of commercial software, unless your in a work environment that uses a particular commercial program it may not be necessary to ever buy or use Office 365. There are many alternatives including;

LibreOffice – Looks and acts just like MS Office 2004 (I think it was 2004). It has a word-processer called “Writer”. “Calc,” a spreadsheet program. “Impress,” a presentation program like “PowerPoint”. “Draw,” is a program for creating diagrams like “MS Visio.” “Base,” a database program like “MS Access.” There is a math equation editor called “Math,” similar to, I think it’s called “Equation.” Libre Office uses the “Open Document Format,” or ODF, but you can open and edit Microsoft documents. You can also save ODF documents to Microsoft formats, although I’ve heard of some formatting issues. I personally have not experienced this. There are many lesser known desktop alternatives but LibreOffice is the big one.

Office Alternatives In The Cloud

Other popular alternatives to MS Office are cloud applications like:

Google Apps including GMail, Google Drive, Google Docs, Sheets, Calendar and more. There is a commercial version called Google Workspace which has a ton of functionality. This is what I use being integrate in to the Google universe .

My other favorite free cloud suite is by Microsoft itself. Office.com includes, Outlook Mail, Teams, a video chat client like Zoom. OneDrive, cloud storage, like Google Drive. The usual Microsoft Office applications like Word, Excel, PowerPoint, OneNote, and others. All of these applications are very similar to the desktop applications without some of the bells an whistles that are seldom used. Those use to MS Office will be very comfortable here.

Other Alternatives

There are a lot of other alternatives but the aforementioned are the are the most popular.

You can find more alternative software be visiting AlternativeTo.