When an electron beam irradiates a sample, what processes occur inside the material to ultimately produce Cathodoluminescence (CL)? Starting from the fundamental principles of cathodoluminescence, this webinar introduces coherent and incoherent luminescence, intrinsic and impurity-related luminescence, and localized surface plasmon resonance. Combined with examples from geology and semiconductor materials, it demonstrates the key research insights that cathodoluminescence provides.