Exceptions are events that arise during the execution of an ABAP program at which the program is interrupted, because it is not possible to continue processing the program in a meaningful way. Exception handling enables you to react to these events.
Exception situations can be recognized either by the program or by the runtime environment. When an exception situation is recognized, either the ABAP program or the runtime environment triggers an exception.
Exceptions are either treatable or untreatable. Untreated exceptions (all untreatable exceptions and all treatable exceptions not caught in the program) lead to a runtime error, which means the program is terminated with a short dump. Treatable exceptions are predefined in the system, or you can define your own.