We have seen how Solver and Goal Seek may be employed to solve single nonlinear equations or simultaneous linear or nonlinear equations through an iteration process. That process iterates on the values of the variables to cause a target function to approach zero. Now, we will see how Solver can be used to maximize or minimize a function subject to a set of constraints that take the form of inequalities. The function that is set as the target is usually called the objective function. Other titles for the objective function may be used depending on the situation they represent, such as cost function (minimize costs), weight function (minimize weight), profit function (maximize profits), etc. The optimization process is normally treated as a subject in operations research, and the mathematical techniques are part of the subject of mathematical programming.