Linkkey｜SNS is a social domain name protocol for Polygon chain, supporting users to register Polygon domain names and issue personal social NFT. Linkkey is officially sponsored by Polygon. Linkkey was officially launched in 2021, won the second place in the NFT category of Polygon Hackathon 2021. $KEY is issued by the user, only 3 years, can be used to register SNS, issue personal social NFT, purchase NFT, etc. These actions will burn KEY.