To exchange means to give something and receive something else in return. When you exchange Halloween candy with your friend, you might trade your chocolate bars for their gummy bears. When stores allow exchanges, they let you swap an item you bought for something different, like exchanging a shirt that doesn't fit for the right size.

The word also refers to the act of trading, the thing being traded, or the place where trading happens. A friendly exchange of ideas means people share thoughts back and forth. A stock exchange is a marketplace where people buy and sell shares of companies.

In conversation, an exchange means a back-and-forth dialogue. You might have a quick exchange with your teacher about homework, or witness a heated exchange between teammates arguing about strategy.

Exchange has powered human progress for thousands of years. Ancient civilizations exchanged silk, spices, and ideas along trade routes. Today we exchange everything from text messages to scientific discoveries.