What is a book?

For the past three years or so, I've read fiction on a kindle and subsequently an iPad. Inverculain and I have bantered about physical or electronic books. What I have found is that if I read on my iPad I tend to look things up on the web and look at blip or play a game. I found that I wasn't concentrating on the book. I thought about this when I dropped into Waterstones the other day in Princes Street for a coffee. So, being the open minded person I believe I am, the next day I decided to visit our small, local bookshop in Bruntsfield and bought a paperback - my first for three years. I'm enjoying reading it and I have to say that my concentration has increased.