Definition of 'Broker'
1. An individual or firm that charges a fee or commission for executing buy and sell orders submitted by an investor.
2. The role of a firm when it acts as an agent for a customer and charges the customer a commission for its services.
3. A licensed real estate professional who typically represents the seller of a property. A broker's duties may include: determining market values, advertising properties for sale, showing properties to prospective buyers, and advising clients with regard to offers and related matters.
Investopedia explains 'Broker'
Traditionally, only the wealthy could afford a broker and access the stock market. The internet triggered an explosion of discount brokers, which allow investors to trade at a lower cost, but don't provide personalized advice. Because of discount brokers, almost anybody can afford to invest in the market.