An intermediary is
- a “middleman” that, before the Internet, was previously required to obtain a good or service: a stock broker, a bank, a medical professional (for information), a travel agent, a store, or a university, to name a few.
- "third parties facilitating a transaction, including those responsible for the storage of information."
- "[a] protocol entity that sits between the initiator and the recipient and is necessary for the initiator and recipient to communicate. Unlike an eavesdropper, an intermediary is an entity that is part of the communication architecture and therefore at least tacitly authorized."