Dual formulation is a mathematical approach used in optimization problems, particularly in linear programming. It involves creating two related problems: the original problem, known as the primal, and a second problem called the dual. The solutions to these problems provide insights into each other, allowing for a deeper understanding of the constraints and objectives involved. In the dual formulation, the dual problem is derived from the primal by associating variables with constraints and vice versa. This relationship helps in determining the optimal solution more efficiently, as solving one problem can yield valuable information about the other. This technique is widely used in various fields, including economics and operations research.