Integrability of a dynamical system is a concept which is widely discussed for a long time in physics, mathematics and somewhat differently in different contexts. It can also be considered as a mathematical property that can be successfully used to obtain more predictive power and quantitative information to understand the system globally. Integrable models form a beautiful class of physical models in the sense that they are exactly solvable. There are various circumstances in which interest in integrability can arise. In past non-linear ordinary and partially differential equations are...