Impulsive light-like signals in General Relativity are, like any models in theoretical physics, idealised mathematical models of objects that can arise in nature. In cataclysmic astrophysical events, such as supernovae and collisions of neutron stars, the final explosion produces a burst of matter travelling with the speed of light accompanied by a burst of gravitational radiation. These are the constituents of a general impulsive light-like signal. The gravitational fields of compact objects such as black-holes or neutron stars also resemble the fields of impulsive light-like signals when the objects are boosted to the speed of light. Spherically symmetric impulsive lightlike signals are useful in the study of gravitational collapse and also in providing classical models of quantum phenomena in black-hole physics such as Hawking radiation and the entropy of a black-hole. Impulsive lightlike signals play a central role in modeling black-hole production in highenergy collisions.