Multi-agent systems (MAS) are composed of loosely coupled entities (agents) interconnected and organized in a network. Every agent has the ability to solve problems and attain its goals by interacting with each other through collaboration, negotiation, and competition patterns. MAS are increasingly dealing with sensitive data. Therefore, enforcing the notion of reputation, ensuring trust and reliability, is essential for modern MAS.
Blockchain (BCT) is a P2P distributed ledger technology providing shared, immutable, transparent, and updatable (append-only) registers of given values characterizing a given network (e.g., all the actions intercurred among the participants and information about the participants themselves). However, employing the BCT ``as-is'' and by itself in dynamic and quickly evolving scenarios can represent an unlucky choice. The reasons span from fundamental properties of BCT, to application/domain specific constraints. Reaching consensus in distributed multi‐stakeholder networks with possible unaligned interests can be considerably complex or unsustainable. Therefore, if properly managed, combining BCT and MAS can represent a win-win solution: