A carbon offset is a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide-equivalent (CO2e). One ton of carbon offset represents the reduction or removal of one ton of carbon dioxide or its equivalent in other greenhouse gases. One of the hidden dangers of climate change policy is unequal prices of carbon in the economy, which can cause economic collateral damage if production flows to regions or industries that have a lower price of carbon—unless carbon can be purchased from that area, which offsets effectively permit, equalizing the price. Within the voluntary market, demand for carbon offset credits is generated by individuals, companies, organizations, and sub-national governments who purchase carbon offsets to mitigate their greenhouse gas emissions to meet carbon neutral, net-zero or other established emission reduction goals. The voluntary carbon market is facilitated by certification programs which provide standards, guidance, and establish requirements for project developers to follow in order to generate carbon offset credits. Offsets typically support projects that reduce the emission of greenhouse gases in the short- or long-term. A common project type is renewable energy, such as wind farms, biomass energy, biogas digesters, or hydroelectric dams. Others include energy efficiency projects like efficient cookstoves, the destruction of industrial pollutants or agricultural byproducts, destruction of landfill methane, and forestry projects. Carbon removal offsets include methods based on net-negative products and processes, such as biochar, carbonated building elements and geologically stored carbon. Offsets may be cheaper or more convenient alternatives to reducing individual or organizational fossil fuel consumption. However, some critics object to carbon offsets, and question the benefits of certain types of offsets. Due diligence is recommended to help businesses in the assessment and identification of "good quality" offsets to ensure offsetting provides the desired additional environmental benefits, and to avoid reputational risk associated with poor quality offsets. Features Carbon offsets represent multiple categories of greenhouse gases, including carbon dioxide (), methane, nitrous oxide (N2O), perfluorocarbons, hydrofluorocarbons, and sulfur hexafluoride. Carbon offsets have several common features: Vintage. The vintage is the year in which the carbon emissions reduction project generates carbon offset credits. Credit generation typically occurs following third party review (also known as verification) as conducted by a validation-verification-body, designated operational entity, or other accredited third party reviewers. Typically, projects generate credits for emissions reducing activities