A beaver is a large rodent famous for building dams across streams and rivers. These remarkable animals cut down trees by gnawing through the trunks with their strong front teeth, then drag the logs into the water to construct elaborate dams and dome-shaped lodges where they live. A beaver's dam can completely transform a landscape, turning a flowing stream into a calm pond.

Beavers are one of the largest rodents in the world, about the size of a medium dog, with distinctive flat, paddle-shaped tails they use for swimming and slapping the water to warn other beavers of danger. They're native to North America and parts of Europe, and their engineering skills are so impressive that their dams can last for decades. The ponds created by beaver dams provide homes for fish, frogs, ducks, and many other animals.

In American history, beaver fur was so valuable for making felt hats that trappers explored much of North America searching for beavers, helping to open up the continent. The phrase eager beaver describes someone who's especially enthusiastic and hardworking, inspired by how tirelessly these animals work on their construction projects.