E-books can be read on many devices, including e-readers such as the Kindle or Nook, tablets such as the iPad, and computers. E-books in the MOBI format can be read on Kindle apps and e-readers. E-books in the EPUB format can be read on all other devices.
To load the Kindle e-book in any Kindle device, Kindle app, Kindle cloud reader, the most convenient process is to use the Kindle Personal Documents Service. This service will allow the file to be treated like any Kindle e-book you purchase from Amazon, including syncing your bookmarks, reading location, highlights, etc., between your devices.
To load the EPUB file in iBooks on Apple devices, add it to your iTunes library choosing File > Add to Library, or drag the EPUB file to the Books Library in iTunes on your computer. Then sync your device with iTunes to add the book to your iBooks Library. Alternatively, if you purchase using your iPad/iPhone directly, downloading the file will open a dialog on your device asking if you want to load the file in iBooks.
Here is a helpful video about how to sideload the EPUB file on a Nook device.
To load the EPUB file on a Kobo device, use the Kobo Desktop application.
You can also sideload the e-book file, either the MOBI for Kindle readers or EPUB for other readers, from a computer directly to the e-reader. To do this, first identify the downloads folder used by your web browser. Then connect your e-reader to your computer using the USB port. You can then find the e-book file in your downloads folder, copy it, and paste it to the e-reader folder.
You can also read e-books on a computer. You can install stand-alone software such as Calibre, Adobe Digital Editions, Kindle, or Nook. There are also web browser extensions and apps available for Chrome, Firefox, Safari, and Edge that will let you read e-books in a browser.