What apps are the best for reading PDFs on my iPhone or iPad?
There are many options out there, but here are a couple:
PDF
Many eBooks are formatted as PDFs, and thus require no additional software to view.
DRM
However, some of our eBook platforms use digital rights management (DRM) to limit what a user can do with the content. This prevents wide-scale distribution of electronic content or printing of large amounts of text in order to protect the publisher/author's income stream. Still, most platforms allow some limited use of their content on mobile devices
Nook
Transfer PDF files from your computer to your ereader by simply plugging in your reader to the computer and dragging and dropping into the device. This way the PDF automatically becomes part of your library, rather than just a "download."
Kindle