The term "mediator" is from a software architecture design pattern to reduce chaotic dependencies between components. Mediators are DIDComm agents that act as a proxy for other agents and are part of the DIDComm Messaging Specification from the Decentralized Identity Foundation.

Using a Mediator Service, two agents (wallets or other services) can communicate with each other without having to know each other's IP address. Like other DIDComm connections, a mediator connection with your wallet is end-to-end encrypted.

The Blocktrust Identity Wallet setup steps allow you to opt in to connect with the Blocktrust Mediator Service. This connection will be used for messages you receive. You can optionally set up one or more mediator connections via the wallet settings.