Much of the confusion in carbon neutral standards can be attributed to the number of voluntary carbon standards which are available. For organizations looking at which carbon offsets to purchase, knowing which standards are robust, credible and permanent is vital in choosing the right carbon offsets and projects to get involved in. Some of the main standards in the voluntary market include; The Verified Carbon Standard, The Gold Standard, The American Carbon Registry, The Climate Action Reserve, and Plan Vivo. In addition companies can purchase Certified Emission Reductions (CERs) which result from mitigated carbon emissions from UNFCCC approved projects for voluntary purposes. The concept of shared resources also reduces the volume of carbon a particular organization has to offset, with all upstream and downstream emissions the responsibility of other organizations or individuals. If all organizations and individuals were involved then this would not result in any double accounting.