Fiber-optic Fabry-Perot (FFP) sensors boast notable advantages over other optical fiber sensors, including their immunity to electromagnetic interference, high resolution, compact size, and low cost. This book offers a complete overview of FFP sensing technology, integrating the knowledge and tools of multiple fields including optics, sensing, micromachining, instrumentation, physics, and materials science. The main chapters discuss operating principles, microstructures, fabrication methods, signal demodulation, instrumentation, and applications.