According to online reports, Ethereum co-founder Vitalik Buterin wrote "Why I used to prefer permissive licenses and now favor copyleft", which pointed out that he has always supported permissive licenses, hoping to maximize the adoption and dissemination of works, and publishing with a permissive license will help achieve this, because the permissive license clearly states that if anyone wants to develop based on my work, there is no need to worry about any problems. In addition, he does not like copyright from a philosophical perspective, but appreciates the left-wing concept of copyright of "using copyright against oneself." However, this idea has now changed and has begun to pay more attention to Copyleft, because open source has become the mainstream, and it is more practical and feasible to promote enterprises to open source. Companies such as Google, Microsoft and Huawei are all embracing open source. Secondly, competition in the cryptocurrency field has become increasingly fierce and mercenary. (Note: Copyleft is a concept and licensing method that is opposed to traditional copyright Copyright. Copyleft licensing requires derivative works based on the original work, and must also be open and open in the same licensing method, so that the work remains open and open in the process of dissemination and development. Features of sharing)