Yes it is true that you can read online books for free from some web sites. There are about 30 of them available at desiringgod.org. All of these books are good and worthy of reading.
One of the problems I have always had in reading books in PDF format is that I would lose my place. It is hard to put a book mark on an electronic document. Perhaps most people know that you can get a plug in for book marks for PDF, but unfortunately I did not think of that till the other day when I was reading a book that I wanted to book mark.
Well I just thought I would “google” bookmark plug in for PDF and sure enough I found a few. Here is a link to one that works well if you follow the installation instructions. I am sure that there are many others like it. This one is free and it works, two qualities I find attractive in software.
So if you have been reluctant to read free books in PDF format because you could not remember your place, try a plug in and read on!