Recent years have seen digital advertising grow to the point where it will soon overtake television as the no. 1 advertising medium. In the online environment, consumers interact and share their thoughts on brands and their experiences using them. These electronic word-of-mouth (e WOM) communications have become a very important to the success of products. In today’s cluttered environment, it is especially important to study how the practice of e WOM advertising operates, and how marketers can influence e WOM in social media and other online sites. This volume starts with a chapter on the current state of knowledge on e WOM and then turns its attention to current research articles on a variety of e WOM formats. These include the posting of selfies on social media, the influence of review types on consumer perception and purchase intention, the effects of preannouncement messages, and how user-generated content can be used to induce effectiveness of e WOM on social media. The relationship of e WOM to brand building is emphasized in several of the chapters. This book was originally published as a special issue of the International Journal of Advertising.