Ecological footprint (EF) analysis is a measure of human emand on the Earth's ecosystems and natural resources. It compares human consumption of natural resources with planet Earth's ecological capacity to regenerate them. It is an estimate of the amount of biologically productive land and sea area needed to regenerate (if possible) the resources a human population consumes and to absorb and render harmless the corresponding waste, given prevailing technology and current understanding. Using this assessment, it is possible to estimate how many planet Earths it would take to support humanity if everybody lived a given lifestyle. While the ecological footprint term is widely used, methods of measurement vary quantitatively.