The GlobalSearch and MultiStart solvers apply to problems with smooth objective and constraint functions. The solvers search for a global minimum, or for a set of local minima. For more information on which solver to use, see Choosing a Solver.
GlobalSearch and MultiStart work by starting a local solver, such as fmincon, from a variety of start points. Generally the start points are random. However, for MultiStart you can provide a set of start points. For more information, see How GlobalSearch and MultiStart Work.
To find out how to use these solvers, see Optimization Workflow.