Controlling is a fundamental managerial function that involves ensuring performance meets plans and standards. It is a continuous process that is forward-looking and linked to planning. There are four main areas of control: physical resources, human resources, information resources, and financial resources. Control can be classified as man and machine or organizational and operational. The basic control process involves setting standards, evaluating performance against standards, and taking corrective actions. Advantages include ensuring goals are met and facilitating improvement, while limitations include imperfect measurements and human reactions.