Glossary
Soulbound Token (SBT)
A non-transferable token bound permanently to one account — used for credentials, badges, attestations, and reputation that shouldn't be tradeable.
A soulbound token is an NFT (or ERC-20) that cannot be transferred after mint. The term comes from a 2022 paper by Glen Weyl, Puja Ohlhaver, and Vitalik Buterin arguing that on-chain identity needs non-transferability to be meaningful — a university diploma loses its meaning if it can be sold.
ERC-5114 and ERC-5484 formalize the pattern. Use cases: proof of attendance (POAPs predate the term), credentials, governance attestations, gated access. The downside is recoverability — a lost key means a lost identity.