An intermediary is a third party that offers intermediation services between two trading parties. The intermediary acts as a conduit for goods or services offered by a supplier to a consumer. Typically the intermediary offer some added value to the transaction that may not be possible by direct trading.
Common usage includes the insurance and financial services industry where mortgage brokers, insurance broker, and financial advisers offer intermediation services in the supply of financial products such as mortgage, insurance and investment products.
In barter, an intermediary is a person or group who stores valuables in trade until they are needed, parties to the barter or others have space available to take delivery of them and store them, or until other conditions are met. In a larger sense, an intermediary can be a person or organization who or which facilitates a contract between two other parties.