A carbon footprint is "the total set of greenhouse gas (GHG) emissions caused by an organization, event, product or person."[1] Greenhouse gases can be emitted through transport, land clearance, and the production and consumption of food, fuels, manufactured goods, materials, wood, roads, buildings, and services.[2] For simplicity of reporting, it is often expressed in terms of the amount of carbon dioxide, or its equivalent of other GHGs, emitted. (Source: Wikipedia).
Visualization of a metric ton of carbon dioxide