This tutorial explores the fundamentals and cutting-edge applications of Distributed Optical Fiber Sensing (DOFS) technologies, specifically focusing on Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS/DTGS). Based on Rayleigh and Raman s principles and phase-sensitive OTDR (phi-OTDR), these technologies enable real-time, high-sensitivity monitoring of acoustic, strain, and temperature variations along several kilometers of standard optical fibers. Participants will gain insights into the implementation challenges and technical specifications of these systems, longside practical case studies in critical sectors. The session highlights diverse applications including leak detection in pipelines and refineries, structural health monitoring of dams and offshore wells, seismic tomography, and thermal imaging of power generators, demonstrating the transformative potential of DOFS for the safety and efficiency of modern energy and infrastructure systems.