In optimization, the line search strategy is one of two basic iterative approaches to find a local minimum of an objective function . The other approach is trust region.

The line search approach first finds a descent direction along which the objective function will be reduced and then computes a step size that determines how far should move along that direction. The descent direction can be computed by various methods, such as gradient descent, Newton's method and Quasi-Newton method. The step size can be determined either exactly or inexactly.