Define controlling and its elements.

Controlling is one of the managerial function. it is an important function because it helps to check the errors and to take the corrective action so that deviation from standers are minimized and stated goals of the organization are achieved in desired manner.
Terry and Franklin "Controlling is determining what is being accomplished - that is evaluating performance and if necessary applying corrective measures so that the performance takes place according to plans. "
Fenry Fayol "Control of an undertaking consists of seeing that everything is being carried out in accordance with the plan which has been adopted, the orders which have been given, and the principles which have been laid down. Its object is to point out mistakes in order that they may be rectified and prevented from recurring "

Elements of controlling:

There are four basic elements of control:

• The condition characteristic to be controlled: the first element is the characteristic or condition of the operating system which is to be measured. Three is a specific correlation between the characteristic to be controlled and how the system is performing. for ex the hours a teacher works or the gain in knowledge demonstrated by the students on a national examination are examples of characteristics that may be selected for measure, or control. 
• The sensor: It is a means for measuring the characteristics or condition. it is must for the controlling system to include sensor while designing as a method of measurement. for ex in quality control system this measurement might be performed by a visual inspection of the product.
• The comparator:  It determines the need for corrective measures after having comparison between what is occurring what has been planned. Some variation is expected but if it goes beyond parameters than corrections need to be done.
• The activator: It is the corrective action taken to return the system to expected output.