Influence

This book has been most insightful, for me it was the second most influential book after Covey's Seven habits. It is about understanding how people get us to say “Yes” when we should have said “No”.

Not just about marketing/advertising, this is a book for everyone. Because we all face situations when we are influenced by other people (or need to influence other people). And this book helps us become more rational when making decisions, avoiding those pitfalls of influence.