The holographic correspondence between non-gravitational field theories and gravitational theories in one higher dimension can be used to study non-equilibrium behavior of strongly coupled quantum field theories. One such phenomenon is that of quantum quench, where a coupling of the field theory is time dependent and typically asymptotes to constants at early and late times. In the gravity dual this can describe, under suitable circumstances, either black hole formation, or passage through a spacelilke region of high curvature similar to a cosmological singularity. On one hand this has taught us about the meaning of cosmological singularities, while on the other hand this has thrown light on the process of thermalization in strongly coupled field theories. In particular in recent work holography has been used to study situations where quantum quench happens across a critical point, and has revealed interesting scaling properties.