The debt ceiling is a limit set by the U.S. Congress on how much money the federal government is allowed to borrow. This borrowing is necessary to cover expenses that exceed the government's revenue, such as funding for programs, salaries, and interest on existing debt. When the ceiling is reached, the government cannot borrow more money unless Congress raises or suspends the limit. When the debt ceiling is not raised, the government may face a default, meaning it cannot meet its financial obligations. This could lead to serious economic consequences, including a loss of investor confidence and potential increases in borrowing costs for the government and consumers.