The book introduces the broad realm of structural health monitoring, with a thorough discussion of SHM systems, processes, and management tools. It continues with the main focus of the book Fibre-Optic Deformation sensors, their application and interpretation, covering areas such as the mechanical parameters to be monitored - deformations, displacements, rotations, cracks openings, curvatures, with in depth discussions of how to achieve the monitoring aims, how to make data interpretation depending on the construction material, and discusses what numerical concepts and formulas to use in order to properly analyse the data. Overall the Book is organised so that it can be used as a step-by-step guide to implement a monitoring system and includes numerous application examples on the most common types of structures, such as building, bridges, historical monuments, piles, dams, tunnels, pipelines, risers, and off-shore structures, and their most frequently monitored parameters.