In general, a broker is an independent agent 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 broker who facilitates the sale of a property.rokers may represent either the seller (90% of the time) or the buyer (10%) but not both at the same time. An example would be a stockbroker, who makes the sale or purchase of securities on behalf of his client.