Online advertising expenditures now surpass those allocated to some traditional media such as billboards. Despite this, little is know regarding how advertising works in the online environment. This book, written by two leading PhD researchers in the field, is the first study of how advertising frequency and variation impact consumer attitudes online. In addition, this book employs a pioneering method that uses real web advertisements for real brands in a systematic investigation. The results of this book prove that traditional advertising theories and practices developed for offline media require adaptation to be used successfully online. Advertisers and researchers will find this book must reading as the web advertising medium continues to grow.