Carbon accounting (or greenhouse gas accounting) is a framework of methods to measure and track how much greenhouse gas (GHG) an organization emits. It can also be used to track projects or actions to reduce emissions in sectors such as forestry or renewable energy. Corporations, cities and other groups use these techniques to help limit climate change. Organizations will often set an emissions baseline, create targets for reducing emissions, and track progress towards them. The accounting methods enable them to do this in a more consistent and transparent manner. GHG accounting is often done to address social responsibility concerns, or meet legal requirements. Other motivations include public rankings alongside other companies, financial due diligence, and potential cost savings. GHG accounting methods can help investors better understand the climate risks of companies they invest in. Corporate and community net-zero goals are also aided by accurate accounting methods. There are now many governments around the world that require various forms of reporting, and there is some evidence that programs that require GHG accounting have the effect of lowering emissions. Markets for buying and selling carbon credits also depend on accurate measurement of emissions and emission reductions. These techniques can also help understand the impacts of specific products and services by quantifying their GHG emissions throughout their lifecycle. This can promote more environmentally friendly purchasing decisions. These techniques can be used at different scales, from those of companies and cities, to the greenhouse gas inventories of entire nations. They typically involve a combination of measurements, calculations, estimates, and reporting. A variety of standards and guidelines can apply, including Greenhouse Gas Protocol and ISO 14064. These often organize emissions into three categories. The Scope 1 category covers direct emissions from an organization's facilities. Scope 2 covers emissions from electricity purchased by the organization.