A trader is someone who buys and sells things to make money. The concept is simple: a trader purchases goods where they're available or cheap, then sells them where they're needed or more expensive. If a trader buys baseball cards for two dollars each and sells them for three dollars, they make a one-dollar profit per card.

Throughout history, traders have connected different parts of the world. Medieval traders traveled dangerous routes to bring spices from Asia to Europe. Colonial traders exchanged furs, tobacco, and manufactured goods between continents. These traders didn't make the products themselves; they moved goods from where they were abundant to where people wanted them, making the world more connected.

Today, many traders work with stocks, bonds, and other financial investments rather than physical goods. A stock trader might buy shares in a company hoping the price will rise, then sell them at a profit. These traders often work at computers, watching prices change minute by minute. Some traders work for big banks or investment firms, while others trade independently.

The word can also describe anyone who exchanges one thing for another, like kids who trade sandwiches at lunch or collectors who trade duplicate cards. When you make a trade with a friend, you're both acting as traders, each hoping to end up with something you value more than what you gave up.