The above statement refers to the fact that earth belongs to everyone, from our ancestors to our future generations. It indicates towards the point that the planet earth should be protected and conserved in the same way as by our ancestors, so that it can be passed on to our future generations. It highlights an underlying problem which is the over-exploitation of resources by the present generation which could eventually lead to the destruction of life on earth. The planet earth can be protected for future generations by following the path of sustainable development. Sustainable development means that development should be such that it can be sustained for longer period of time and must cater to the needs of the coming generations. It is mostly used in terms of the non-renewable sources of energy, which face depletion because of over-use by human beings. Sustainable development seeks to promote a judicious use of non-renewable energy sources such as coal and petroleum so that they do not get depleted beforehand and our future generations do not have these resources at their disposal. Sustainable development thus means developing in such a way that not only our present but our future is also secured.