A carbon market is a market mechanism that allows for the buying and selling of carbon credits, which are units of measurement for greenhouse gas emissions. The goal of a carbon market is to incentivize companies and individuals to reduce their carbon emissions and promote the use of renewable energy sources. This is often done through a system of cap-and-trade, where a government or regulatory body sets a limit on the amount of emissions allowed and companies can buy or sell carbon credits to meet their emissions targets.