Definition: "Exception is a runtime error which arises because of abnormal conditions in a code sequence". In C# Exception is a class in the system namespace. An object of an exception is that describe the exceptional conditions occur in a code That means, we are catching an exception, creating an object of it, and then throwing it. C# supports exceptions in a very much the same way as Java and C++.

Before going into detail, I must say the usefulness of knowing and performing exception handling :

• They cannot be ignored, as if calling code does not handle the error, it causes program termination.
  
• They do not need to be to be handled at the point where error took place. This makes them very suitable for library or system code, which can signal an error and leave us to handle it
  
• They can be used when passing back a return value cannot be used.