Ecological footprint is a tool to measure the amount of resources required by a human population to produce the resources that it consumes, and also the resources required for absorbing the waste that is produced from resource consumption. It is a method of comparing human demand with the capacity of the planet's ecology to regenerate the consumed reserves. The Method of Calculation In 1992, William Rees, a professor at the University of British Colombia, published information about the ecological footprint for the first time. At the University of British Colombia, Rees along with Mathis Wackernagel developed the method of calculation. They came up with the idea of 'appropriated carrying capacity' and Rees later named it as the ecological footprint. In four years that was in 1996, they published a book on this subject. For us to thrive, we need food, water, and other natural resources. Every act of consumption of the natural resources largely impacts their amounts in nature. An excessive consumption of nature's resources leads to their depletion. Depletion of resources becomes a major concern for mankind when the consumption crosses the limit of nature's capacity to produce. The ecological footprint is measured by assessing the biologically productive land and marine area that is necessary to generate the resources. The measurement also takes into account the natural resources that are required to absorb the waste produced as a byproduct of the process of consumption. The ecological footprint is measured by comparing the resource consumption by the people of a certain nation, with the amount of resources available within that region. The measurement involves an analysis of people's lifestyles. Per capita ecological footprint is a way of comparing the consumption by human beings with the planet's capacity to reproduce the consumed resources. This tool helps in the analysis of the extent to which a nation uses more or less than what is available in the nation's territory. It is the means by which humans can be educated about the carrying capacity of nature and it alerts mankind about overly consumed natural resources. Ecological footprint can be used as a tool to warn the nations about the excessive use of natural resources by their natives. The tool is of great use in the study of current lifestyles and analyzing the right kind of lifestyle that can suit a particular population. Studies show that the ecological footprint of today is 23% larger than our planet can produce. In simpler words, the Earth takes a period of around 1 year and two months to regenerate all that is consumed in one year. This scenario where our demands exceed the regenerative capacity of nature, is termed as an ecological overshoot. Limitations According to critics, the measurement of ecological footprint does not take into account the side effects of trade practices, urbanization, the differences between the ways of energy generation and consumption, and other similar factors which contribute to shaping the lifestyle of a populace. It ignores the fact that farmers in rural areas are bound to consume more resources in transportation and in making up for the insufficiency of other needful resources. In this, they may be seen as consuming more than their urban counterparts while the contrary is true. Ecological footprint fails to differentiate between various ways of energy production, when the production of waste products in different processes is dissimilar. Critics say that ecological footprinting is not all-inclusive. The method of measurement fails to weigh the factors responsible for the consumption and regeneration of biological resources. True, ecological footprint does not facilitate foolproof measurement, but it provides us with an understanding of the production, consumption, and wastage of natural resources. Measuring the ecological footprint of a population can help us reflect on our ecological assets. It enables a population to take curative actions towards a careful and responsible use of natural resources. It helps people think about the preventive measures to save the environment. It is a tool that helps mankind contemplate living.