How to use ebook files
pdf and ePub
Most browsers can read pdf files, including Firefox, Chrome, and Safari.
There are also many different software options for reading pdf files.
On Windows: Adobe Acrobat Reader works well enough, though there may be better options as well.
The ePub format is an open format for ebooks.
An advantage to ePub over pdf is that you can change the size of the fonts. On the better ePub readers, such as those mentioned below, you can expand the images and then minimize them again, which is very helpful.
On Appe products, such as Mac or iPad, or even iPhone, the best app for reading ePub files is: Apple iBooks, which comes preinstalled on both MacOs and iOS (iPad and iPhone)
On Windows and Linux, that best app that for reading ePub is: Calibre