A broker's commission is a fee charged by a broker for executing a trade on behalf of an investor. The commission is typically calculated as a percentage of the total trade value and can vary depending on the broker, the investment type, and the specific trade. For example, stock trades may have a different commission rate than options trades. Commission rates can also be impacted by factors such as the size of the trade, the frequency of trades, and the level of service provided by the broker. Some brokers may offer lower commission rates for high-volume traders or for clients who maintain a certain account balance. It is important for investors to be aware of the commission rates charged by their broker and to factor these fees into their investment decisions.