Earlier, cultivation was the only source of livelihood for people, thus, demand for environmental resources was lesser than the supply. Naturally, the wastage was also less and within the absorption capacity of the environment. Today, with the advent of industrial revolution and population explosion, more and more resources of the environment is being depleted to meet the growing and diversified demands of the people. This leads to depletion of the resources faster than the regeneration capability of the environment. Hence, the demand for the environmental resources is high whereas the supply has diminished. Thus, alternative resources are being tapped or developed to reduce this demand and supply gap.