An intermediary (or go-between) 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 offers some added value to the transaction that may not be possible by direct trading.
Common usage includes the insurance and financial services industry where e.g. mortgage brokers, insurance broker, and financial advisers offer intermediation services in the supply of financial products such as mortgage loans, insurance, and investment products