Stock Market Basics: How the Stock Market Works — A Complete Introduction

Order Types Explained

Choosing the right order type determines how your trade gets executed. Each type balances speed, price certainty, and execution guarantee differently.

Market order: Buy or sell immediately at the current best available price. Execution is guaranteed, but the final price may differ from the last displayed price — especially in fast-moving markets. Use when getting into or out of a position quickly matters more than the exact price.

Limit order: Buy or sell at a specified price or better. The order sits on the exchange's order book until the price reaches your level. Price is guaranteed, but execution is not — the market may never reach your limit. Use when you want to buy at a specific price and are willing to wait.

Stop order (stop-loss): Becomes a market order when the price hits a specified trigger level. Used to limit losses — if you own a stock at $100 and set a stop at $90, a market sell order triggers automatically if the price drops to $90. Execution is likely but price is not guaranteed — in a fast drop, your fill could be below $90.

Stop-limit order: Becomes a limit order when the price hits the stop trigger. More control than a stop order — you specify both the stop price and the limit price. The order will only fill at the limit price or better, but if the market gaps past your limit, the order may not execute at all. Use when you want to control the minimum sell price.

Market Hours and Key Indices

The stock market operates on a fixed schedule. Regular trading hours are 9:30 AM to 4:00 PM Eastern Time, Monday through Friday (excluding holidays). Pre-market trading runs from 4:00 AM to 9:30 AM ET, and after-hours trading from 4:00 PM to 8:00 PM ET. Volume is significantly lower outside regular hours, spreads are wider, and prices can be more volatile. Most individual investors should stick to regular hours for better liquidity and price discovery. Dollar-cost averaging works best during regular market hours →

Three major indices track US stock performance. The S&P 500 includes the 500 largest publicly traded US companies by market capitalization and is the most widely followed benchmark for the overall market. The Dow Jones Industrial Average tracks 30 blue-chip companies (Apple, Microsoft, Goldman Sachs) using a price-weighted formula. The NASDAQ Composite includes over 3,000 stocks listed on the NASDAQ exchange, with a heavy technology and growth company concentration. These indices are not investable directly, but ETFs like VOO (S&P 500), DIA (Dow), and QQQ (NASDAQ 100) let you invest in them. See how index ETFs compare to other investments →

Real-World Example: Buying Apple Stock

Scenario: You decide to buy 10 shares of Apple (AAPL) at $200 using a market order through your brokerage account. Here is exactly what happens. You open your broker's trading interface, enter AAPL, select 10 shares, and submit a market order. In less than a second, your order reaches the exchange or market maker. The best available ask price is $200.01, so your total cost is $2,000.10. Most modern brokers charge $0 commission on stock trades. Apple now appears in your portfolio. As a shareholder, you are entitled to Apple's dividend of $0.25 per share per quarter — $2.50 per quarter on your 10 shares, or $10 per year. If the stock price rises to $250, your 10 shares are worth $2,500 — a $499.90 profit. You can sell your shares anytime during market hours by placing a sell order. The entire process, from decision to ownership, takes less than 60 seconds.

How much money do I need to buy stocks?

You can start with as little as $1 if your broker offers fractional shares. Without fractional shares, you need enough for at least one share of the stock you want to buy — ranging from a few dollars for penny stocks to hundreds for blue chips like Apple or Microsoft. Most brokers have no minimum deposit, so you can fund your account with any amount. A practical starting point is $100 to $500, which lets you buy fractional shares of a diversified ETF like VOO (S&P 500) for instant diversification.

What's the difference between a stock and a share?

A stock refers to the general concept of ownership in a company — "I own stock in Apple." A share is a specific unit of that ownership — "I own 10 shares of Apple." When people say they own stock, they mean they own shares. The terms are used interchangeably in practice, but technically: stock is the asset class, and a share is the individual unit. Companies issue a fixed number of shares (outstanding shares), and each share represents an equal fraction of ownership in the company.

Can I buy fractional shares?

Yes, most modern brokers now offer fractional shares, allowing you to buy a dollar amount of a stock rather than a whole number of shares. Instead of buying 1 share of Apple at $200, you can buy $50 worth (0.25 shares). This is especially useful for building diversified portfolios with limited capital — you can spread $100 across several high-priced stocks or ETFs. Brokers including Fidelity, Schwab, Robinhood, and Interactive Brokers offer fractional share trading. Fractional shares have the same rights as whole shares, including dividends proportionally.

What happens if a stock I own goes to zero?

If a stock goes to zero, your entire investment in that stock becomes worthless. This happens when a company goes bankrupt and is liquidated — shareholders are last in line to receive any remaining value, after bondholders and other creditors. In most bankruptcies, common stock becomes completely worthless. This is why diversification is critical: if you own 20 stocks and one goes to zero, you lose 5% of your portfolio. If you own a single stock and it goes to zero, you lose everything. Holding a diversified ETF is the safest way to avoid total loss from any single company's failure. Compare brokers that offer commission-free diversified investing →

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