If you would like some explanations for why Google AdWords has the policies they do and their evolution over time, it is quite helpful to pick up these two books from Barnes and Noble or on Amazon. I read the second by sitting in B&N two afternoons straight (I then had then office manager purchase two copies for the marketing team). I was so hooked. 1. Winning Results with Google AdWords by Andrew Goodman 2. The Ultimate Guide to Google AdWords by Perry Marshall I would say Goodman's book is excellent for AdWords history as well as some great strategies, schools of thought, and tips. The first 4 chapters give an interesting history of the Internet and PPC in general. Goodman's book is probably better for beginners (although just slightly outdated). The only difference now is you can go below a .05 click-through-rate and your keywords will remain active. I've read Goodman's book twice and now read his blog (he doesn't get that deep about tips in there, but it's interesting). traffick.com Marshall's book is very much hard core tips for someone ready to make $ now using AdWords and using it as a facilitator for creating a sales machine and squeezing every last bit of potential out of your ads and keywords. He'll also tell you some tips that Google probably doesn't want you to know (using broad, exact, and phrase matching on every keyword), because it saves you $ and they don't get as much per click.