US Investment Brokerage. If you want to invest actively, you'll need a brokerage firm.
A brokerage firm is a group of stock brokers who buy and sell your shares on the open market (hint: buy low, sell high). The services of a stock broker, a trained, licensed professional at a brokerage firm, are necessary to buy or sell in your name. What, you say? Sounds like a monopoly? Scottrade. TD AMERITRADE.