When is a book not a book

I've spent part of today buying books on my iPhone. I haven't read a full one on my phone as yet, but I am now partly committed. It seems a shame - I like a rummage (well, a careful, section-based. alphabetical browse) in a bookstore, but the fact pretty much is that in Glasgow city-centre boasts only two bookstores, one brand, two beaches. Supermarkets and other alternatives are available, but I use my phone quite a lot for other things, so reading just seemed the next step. Yes, I'm now using my phone as a book.