A stock market is essentially a giant marketplace. Instead of buying and selling fruits or antiques, people buy and sell tiny pieces of ownership in companies. These pieces are called shares, or stocks.

Why does this market exist? For two main reasons. First, it allows companies to raise money, or capital, to grow their business. By selling shares, they get cash to fund new projects, hire more people, or expand operations. Second, it gives investors a chance to own a part of those companies and potentially grow their own wealth. If the company does well, the value of its shares may go up.

Trading doesn't just happen in the abstract. It takes place in specific venues called stock exchanges. Think of them as the official arenas for buying and selling stocks. Each country has its own, but some of the most well-known are in the United States.

The New York Stock Exchange (NYSE) is one of the oldest and largest. It traditionally operated as a physical auction, with traders shouting orders on a bustling floor. While much is electronic now, that floor still exists.

The NASDAQ is another major U.S. exchange. Unlike the NYSE, it has always been a fully electronic market. There's no physical trading floor. All trades happen through a vast network of computers. It's known for listing many of the world's biggest technology companies.

You can't just walk onto the floor of the NYSE and start buying shares. Individual investors need a go-between to access the stock market. This intermediary is called a broker.

To start investing, you open a brokerage account. This is a special type of account designed to hold your investments. You fund it with money, and then you can use that money to place orders through the broker's platform to buy and sell stocks. Today, most brokers are online, making it easy to manage your account from a computer or smartphone.

With thousands of companies to follow, how can anyone tell if the market is generally doing well or poorly on any given day? That's where stock indices come in. An index is a curated list of stocks that provides a snapshot of the market's overall performance. It's like a report card for a section of the economy.

Two of the most frequently cited indices in the U.S. are the S&P 500 and the Dow Jones Industrial Average (DJIA).

When you hear a news reporter say "the market was up today," they are usually referring to one of these major indices. While they don't tell the full story, they give a quick and useful summary of the market's general direction.

Ready to check your understanding?

Understanding these core components is the first step. You now have a foundational map of what the stock market is, where it operates, how to access it, and how its performance is measured.