The primary purpose of a dam is to control and manage water resources. Dams are built to store water for various uses, including irrigation, drinking water supply, flood control, and hydroelectric power generation. They help regulate river flow, preventing flooding during heavy rainfall and ensuring a steady water supply during dry periods. Additionally, dams can create reservoirs that support recreational activities like fishing and boating. By manipulating water resources effectively, dams play a crucial role in managing ecosystems and supporting human activities.