Coastal zones represent one of the most dynamic and economically productive ecosystems on Earth, yet they are increasingly threatened by accelerating environmental and anthropogenic pressures. Rising sea levels, intensifying tropical storms, shoreline erosion, land subsidence, and unplanned urbanization have increased the vulnerability of coastal populations and infrastructure worldwide. Conventional hard engineering solutions, such as seawalls, groynes, and revetments, have provided localized protection but often at high ecological and financial costs, leading to habitat loss and long-term degradation of natural defenses. Consequently, global attention has shifted toward sustainable, ecosystem-based approaches that integrate ecological processes with human adaptation strategies. This chapter introduces the concept of bioshields, defined as coastal vegetation systems—mangroves, saltmarshes, seagrasses, and coastal dunes—that function as living buffers against hydrodynamic forces while providing multiple ecosystem services. It contextualizes the growing urgency of coastal protection, considering climate change projections and socio-economic dependencies on coastal resources. The discussion situates bioshields within the broader framework of nature-based solutions and resilience theory, emphasizing their capacity to deliver co-benefits including biodiversity conservation, carbon sequestration, and livelihood enhancement. The chapter also outlines the methodological and conceptual foundations of the book, linking physical, ecological, and governance dimensions of coastal management. By framing bioshields as both protective infrastructure and socio-ecological systems, the introduction establishes a scientific and policy rationale for integrating natural defenses into contemporary coastal planning and climate adaptation strategies.