At present, the global carbon trading targets can be divided into two types: allowance and credit.

The European Union officially launched the world's first carbon emission trading system (ETS) in 2005, which is based on allowance trading as the main structure, and is carried out gradually, at the beginning of the implementation of free distribution of carbon emission allowances (EUA) for each enterprise, and then the free allowance is declining year by year, and regulated industries such as manufacturers, power companies and airlines, shipping, etc., need to pay to buy carbon emission permits to make up for their carbon emissions, which need to be obtained through carbon trading.

In contrast, when Taiwan's Environmental Protection Agency revised the Climate Change Response Act, it announced that it would adopt a policy of pragmatically promoting carbon reduction by adopting carbon fees first, coupled with voluntary reduction quota trading, that is, promoting carbon credit trading first, which is different from the path of the EU.