Definition : A Carbon Footprint is historically defined as “the total sets of greenhouse gas emissions caused by an organization, event, product or person.”
When you drive a car, the engine burns fuel which creates a certain amount of CO2 (CO2 is the chemical symbol for carbon dioxide), depending on its fuel consumption and the driving distance.
When you heat your house with oil, gas or coal, then you also generate CO2.
Even if you heat your house with electricity, the generation of the electrical power may also have emitted a certain amount of CO2.
When you buy food and goods, the production of the food and goods also emitted some quantities of CO2.
Your Carbon Footprint is the sum of all emissions of CO2 (carbon dioxide), which were induced by your activities in a given time frame.
Usually a Carbon Footprint is calculated for the time period of a year.