Electronic word of mouth (eWOM) has an effect on trust prior to purchase of similar branding for both highly branded and off-branded products and services. This chapter shows, through a literature review, the impact of eWOM on building trust and then on sales of search and experience goods. Major findings are presented. eWOM has a stronger impact on the sales of experience goods than on search goods. When considering a purchase online, consumers have more resources about the product or service than those that the retailer or manufacturer provides. These newly available resources are consumer-generated; hence, consumers considering a buy find them more trustworthy. Consumers also value differently whether the consumer-generated content is positive or negative about the product or service they are considering buying. The final part of the chapter discusses the different implications for marketing practitioners.