A carbon offset involves a party committed to reducing emissions of greenhouse gases in order to compensate for emissions made elsewhere. The gases involved include carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), sulfur hexafluoride (SF₆), perfluorocarbons, and hydrofluorocarbons. Conversion factors are used to attempt to equate the negative effects of the different gases on the atmosphere. Carbon offsets are typically purchased by either companies or governments under regulations with regard to greenhouse gas emissions or by personal consumers who wish to offset their own contributions to greenhouse gas emissions.