A broker is a person or firm that acts as an intermediary between buyers and sellers. They facilitate transactions in various markets, such as real estate, stocks, or insurance, by connecting clients with the right opportunities. Brokers often earn a commission or fee for their services, which can vary based on the type of transaction. In the financial world, a broker may also provide advice and research to help clients make informed decisions. They can work for large firms or operate independently, and their expertise is valuable for navigating complex markets. Examples include stock brokers and real estate brokers.