This is my preferred book about Google Adwords. It assumes some basic knowledge so it is not for complete beginners. It is well written and thorough. It is now a bit out of date but I would say 90% still remains relevant and I haven't found a book that is better (but I'll keep looking!) - Read more

Today consumers are bombarded by marketing messages almost everywhere they go. If you want to grab someone's attention, you first need to get their permission with some kind of bait. Once a customer volunteers their time, you're on your way to establishing a relationship and making a sale. By talking only to volunteers, Permission Marketing guarantees that consumers pay more attention to the marketing message.  It serves both customers & marketers in a symbiotic exchange. - Read more