An intermediary, also known as a middleman or go-between, is defined differently by context. In law or diplomacy, an intermediary is a third party that offers intermediation services between two parties. In trade or barter, an intermediary acts as a conduit for goods or services offered by a supplier to a consumer, which may include wholesalers, resellers, brokers, and various other services.

In diplomacy and international relations, an intermediary may convey messages between principals in a dispute, allowing the avoidance of direct principal-to-principal contact.^[1] Where the two parties are geographically distant, the process may be termed shuttle diplomacy. Where parties do not want formal diplomatic relations, an intermediary state may serve as a protecting power facilitating diplomacy without diplomatic recognition.^{[citation needed]}

In law, the job of an intermediary involves conveying messages between principals in a dispute, preventing direct contact and potential escalation of the issue. In law, intermediaries can facilitate communication between a vulnerable witness, defendant and court personnel to acquire valuable evidence. Intermediaries can facilitate communication between a vulnerable witness or defendant and court personnel to acquire valuable evidence and to ensure all parties have a fair trial.^{[citation needed]}

In trade, an intermediary middleman or commercial agent 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 which may not be possible by direct trading. Examples of intermediaries are wholesalers and resellers.^{[citation needed]}

Common usage includes the insurance and financial services industries where e.g. mortgage brokers, insurance brokers, and financial advisers offer intermediation services in the supply of financial products such as mortgage loans, insurance, and investment products. In relation to energy supplies, third party intermediaries provide energy-related advice, assistance in purchasing energy and management of energy needs.^[2] In a wider sense, an intermediary can be a person or organization who or which facilitates a contract between two other parties. The interests of commercial agents are protected by legislation such as the EU's Directive 86/653/EEC of 18 December 1986 on the coordination of the laws of the Member States relating to self-employed commercial agents, as implemented within each EU member state. This directive specifically notes that a "commercial agent" is an "intermediary" with continuing authority to negotiate on behalf of another person.^[3]

The internet is creating opportunities to automate the role of an intermediary in many industries.^[4]

Trading intermediaries can be classified as merchant intermediaries or as accountant intermediaries. Bailey and Bakos (1997) analyzed a number of case studies and identified four roles of electronic intermediaries including information aggregating, providing trust, facilitating and matching.^[5][6]

In barter, the 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.

• Disintermediation
• Innovation intermediary
• Internet intermediary
• Non-Registered Intermediary
• Registered Intermediary
• Retail