Dams are made for storing giant amounts of water. In the olden days dams were made from timber, rock and earth but now days they are constructed with concrete.
Dams have to be strong to hold lots and lots of water. Dams are used to store water for electricity and irrigation for crops.
Some dams have footpaths have footpaths and roads on top to get to the other side. Dams have spillways. Dams can be small or huge. Dams normally have a massive lake behind them.