Magnetic Particle Inspection (MPI) is a widely used non-destructive testing (NDT) technique for detecting surface and slightly subsurface flaws in ferromagnetic materials such as iron, nickel, and cobalt. The process uses magnetic fields and magnetic particles (dry or suspended in liquid) to locate discontinuities in materials. In industries where safety and reliability are non-negotiable — such as aerospace, oil & gas, railways, and manufacturing — MPI provides an efficient and cost-effective method for maintaining component integrity.