A broker is an independent party whose services are used extensively in some industries. A broker's prime responsibility is to bring sellers and buyers together and thus a broker is the third-person facilitator between a buyer and a seller. An example would be a real estate or stock broker who facilitates the sale of a property.

Brokers can furnish market research and market data. Brokers may represent either the seller or the buyer but generally not both at the same time. Brokers are expected to have the tools and resources to reach the largest possible base of buyers and sellers.

The word "broker" derives from Old French broceur "small trader", of uncertain origin, but possibly from Old French brocheor meaning "wine retailer", which comes from the verb brochier, or "to broach (a keg)".

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