Although PDF is perhaps the most popular document format on the web, many eBook readers still choose ePub format. The main reason is ePub document is responsive to different screen sizes and font sizes/types are easily adjustable. Plus, you can read en ePub book using various apps including Google Play Books.
Now, you don’t need some expensive software to convert your documents to ePub format, as you can do so via Google Docs.
Write a document in Google Document, or upload an existing Microsoft Word file to your Google Drive, go to File menu and choose download as EPUB publication.
For students, you can even convert your notes into this format and read them using eBook reader apps.