A Broker Is the Bridge Between You and the Market
The confirmation reads "Filled" about two seconds after you tap Buy. In those two seconds, a broker took your order, routed it to a trading venue, and committed your cash — the app just made it look like one motion.
A broker is the person or firm that buys and sells securities on a customer's behalf. You can't walk an order onto an exchange yourself; brokers hold the memberships, the technology, and the licenses that let your trade happen.
What the broker actually does
Behind the button, the broker checks your buying power, routes the order to an exchange or market maker, and reports the fill back to you. Then it settles the trade — cash moves one way, shares the other — and keeps the records your tax forms are built from.
Most retail brokers also provide the brokerage account that holds your cash and investments between trades. Some add research, advice, or retirement tools; others offer little beyond the order screen.
Market order vs. limit order
A market order says "fill this now at the best available price." Quoted at $40, your five shares might fill at $40.05 — that nickel of movement is the price of immediacy, not an error.
A limit order says "only at my price or better." Set a buy limit at $40 and you'll never pay more, but the order can sit unfilled while the stock runs to $45 without you.
How "commission-free" brokers get paid
Zero-commission trades don't make a brokerage a charity. Firms earn from margin loan interest, payment for order flow, interest on idle cash, account fees, and premium subscriptions.
None of that is automatically bad, but it's worth knowing whose incentives sit behind the free button. Full-service firms flip the model: visible fees in exchange for human advice.
The middle ground keeps widening — automated portfolios on one side, bare-bones platforms on the other. That choice gets its own treatment in robo-advisor vs. discount broker.
Checking who's behind the button
Brokers and their reps must register, and the records are public. The SEC's broker overview explains the role, and FINRA BrokerCheck shows a firm's licenses and disciplinary history in a couple of minutes.
Trade Credit Is a Business Tab With a Due Date
Market Risk Is the Tide That Moves More Than One Boat
Before your next trade, look your broker up on BrokerCheck — it's free and takes less time than the trade did.