…the impression left by a foot or shoe on the ground or a surface…
…the amount of fresh water utilized in the production or supply of the goods and services used by a particular person or group…
…the amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, organization, or community…
…the impact of a person or community on the environment, expressed as the amount of land required to sustain their use of natural resources…
