: Open the file using default apps like Apple Books or Google Play Books, or download specialized readers like Moon+ Reader or FBReader.

: Use specialized extractors like The Unarchiver or Keka .

: Drag and drop the file via USB to devices like Kobo or PocketBook (Note: Amazon Kindles typically prefer .mobi or .azw3 , but you can send an EPUB to your Kindle using the official "Send to Kindle" web tool which automatically converts it).

Look at the newly generated file. Depending on how the author originally packed it, you will see one of two things: