In this episode, the topic is Soul Bound Tokens. In the most basic sense, they are just non transferable NFTs. However, SBTs open up quite a few interesting use-case cases for blockchains. Listen to the episode to learn more about what are Soul Bound Tokens and how they could be used in several blockchain applications.
Vitalik’s blog post about SBTs - https://vitalik.ca/general/2022/01/26/soulbound.html