Soulbound Tokens (SBTs)

Soulbound tokens (SBTs) are blockchain-based tokens representing a person's characteristics, features, traits, and achievements. In contrast to NFTs, SBTs cannot be transferred from your soul, i.e., your wallet. Hence, SBTs have a more subtle and less financial use case.

In 2022, Vitalik Buterin made the concept popular. He's the co-author of a highly recommended research paper:

Weyl, Eric Glen and Ohlhaver, Puja and Buterin, Vitalik, Decentralized Society: Finding Web3's Soul (May 10, 2022). Available at SSRN: https://ssrn.com/abstract=4105763