In this book, a brief overview of SHM and the application of FOS are presented. The book focuses on advanced techniques that utilize fiber-optic long-gauge sensing and overcome the limitations of traditional sensing and fulfill the requirements of infrastructure systems. The long-gauge FOSs have the merit of revealing both micro- and macrolevel information. Subsequently, a new approach, areawise distributed monitoring, is thoroughly discussed and its superior performance in SHM demonstrated. Finally, the application of areawise distributed monitoring, combined with the aforementioned long-gauge sensing technique, is presented for groups and networks of complex infrastructure systems.