Some sentences in my work Years ago, a brilliant work by Sommerfeld and Brillouin presented us five kinds of wave velocities: group, phase, front, energy and signal velocity. Each of them has its specific definition. However, in a linear dispersive media, all of them may coincide. In my presentation, we discuss a fascinating behavior: group velocity of light reduced by a very large factor. Or even more intriguing, the group velocity approaching zero. This phenomenon when the group velocity is very slow is known by slow light. When it is approaching zero, frozen light. Slow light is very important in many areas. For instance, optical communications, high performance sensor technologies and digital signal treatment. It is simple to understand the ordinary idea of group velocity. Let's think about two propagating waves,same amplitude A. Both waves have form E = Acos(kiz). The superposition of these waves may be written by E = A(cos(kiz) + cos(kiz)). If one could design a device with a small group velocity, both linear and nonlinear effects would be enhanced. Linear efects scale with the slowdown factor and nonlinear efects scale with its square. The slowdown factor S is the ratio between phase velocity and group velocity. Beyond this simple view, many researchers have shown us interesting and useful results about slow light. Bayindir and Ozbay presented experimental observation of heavy photons at coupled-cavity waveguiding band edges in 3D photonic crystals with extremely small group velocity. Eggleton at al. observed soliton propagation at velocities as low as 0.7c/n.