When you're writing a book you need to have your elevator pitch down or "What's the book about?" will become the most dreaded four words you can hear (followed closely by "how's it going?").
Obviously the one-sentence version of the answer should be something close to the book's subtitle. But I haven't nailed that one down yet, so these days I just say "The economics of zero dollars and zero cents" and hope for the best. Some people glaze over and move on at that point, but for those who stop, intrigued, and ask me to explain, here's what I say:
We all know free--it's a trick that marketers use. But free is changing. When you think about it, there are two economies, one of atoms and one of bits. In the atoms economy, which is to say most of the stuff around us, things tend to get more expensive over time. But in the bits economy, which is the online world, things get cheaper. The atoms economy is inflationary, while the bits economy is deflationary.
The 20th Century was primarily an atoms economy. The 21st Century will be equally a bits economy. This book is about the differences between 20th Century free and 21st Century free--free moving from a marketing trick to a new economic model.
Anything free in the atoms economy must be paid for by something else, which is why so much traditional free feels like bait and switch--it's you paying, one way or another. But free in the bits economy can be really free, with money often taken out of the equation altogether. People are rightly suspicious of free in the atoms economy, and rightly trusting of free in the bits economy. Intuitively, they understand the difference between the two, and why free works so well online.
Today the online world is a country-sized economy built of free. The most interesting business models are in finding ways to make money around free. Sooner or later every company is going to have to figure out how to use free or compete with free, one way or another. My book is about how to do that.