A ton is a unit of weight used to measure very heavy things. In the United States, a ton equals 2,000 pounds, which is about as much as a small car or a fully grown bison. When something weighs a ton, you definitely can't carry it yourself.

The word comes from tun, a huge barrel that winemakers used centuries ago. It held so much liquid that it became a standard for measuring heavy cargo on ships. Today we use tons to weigh everything from trucks and elephants to the amount of steel in a building or the cargo capacity of a ship.

People also use “ton” in everyday speech to mean “a lot,” even when they're not actually weighing anything. If your teacher assigns a ton of homework, she means a large amount, not exactly 2,000 pounds of paper. When you have tons of fun at a party, you're not measuring enjoyment by weight. This informal use captures the word's sense of impressive, almost overwhelming quantity.

Watch out: other countries use different tons. Britain has a long ton (2,240 pounds), and scientists use a metric ton (about 2,205 pounds). But in everyday American conversation, a ton usually means 2,000 pounds.