The Internet has expanded various channel options beyond the traditional physical stores, thus transforming how customers search and purchase throughout the retailing journey. Since its emergence in 2011, omnichannel retailing has increasingly become central to modern shopping, with customers moving freely between online and offline retailing channels before, during, and after purchase. However, many customers still experience inconsistency across channels, leading to dissatisfaction and a tendency to switch channels in search of a more seamless and fulfilling experience. This chapter positions channel switching behaviour as the core of omnichannel customer journeys, challenging the traditional view that switching is only a pattern of channel choice. Instead, we argue that switching behaviour shapes how customers search, evaluate, and purchase across channels. The chapter also sets the stage for our book. The book pursues three key objectives: (1) to explore the reasons behind omnichannel switching behaviour, (2) to identify reasons behind channel choices during switching, and (3) to segment omnichannel switchers for better customer journey design decisions. Set in Vietnam’s electronic goods retailing sector, an early adopter of omnichannel strategies where product involvement is high, the book introduces a rich collection of mixed-methods studies including interviews, focus groups, and online survey. This chapter introduces the book’s research context, aim and objectives, and theoretical and practical contributions that guide the work.