A: A carbon credit represents ownership of the equivalent of one metric ton of carbon dioxide that can be traded, sold or retired. If an organization is regulated under a cap-and-trade system (e.g., the California Cap and Trade Program) it likely has an allowance of credits it can use towards its cap. If the organization produces fewer tons of carbon emissions than it is allocated, the organization can trade, sell or hold the remaining carbon credits. When a credit is sold, the buyer is purchasing the the seller’s allowance of emissions.