If you create an ebook collection out of public domain ebooks, you may find Apple Books on your laptop quite helpful. Also, there is a growing number of ebookstores that offer their books without the DRM, or with the DRM watermark. You can open these files in any epub reader, including Apple Books.
I found Apple Books for Mac particularly useful with handling free samples. I buy ebooks in a couple of ebookstores. They offer free samples, so I pick up epub format and save it to the desktop to read a few pages before deciding whether I want to purchase the title.
Some sites (such as Project Gutenberg) have clear URL addresses of book files. When you tap on a link to the epub format (ending with .epub), you should be able to open it with Apple Books app on your iPad or iPhone.
There's Pages, for example, which is free, already on your Mac, and from which you can publish directly into Apple Books. Also, since the end of Apple's iBooks Author app, has been made ever stronger for writing and publishing ebooks.
I used to use free pdf software for my ebooks before places like Draft2Digital came along and made it easy to convert files into various different formats. This software gives you several options, eg, mobi, epub & pdf.
I create online study material in eBook fomat. But I found that most of students are sharing these ebooks to other for free, by which my sales are decreasing. Is there any way so that an eBook purchased by one can only be opened in their I.P. address ? 2b1af7f3a8