A program that monitors the execution of some software system and provides information on the dynamic behaviour of that system in the form of a trace, i.e. a report of the sequence of actions carried out. Typically a trace program will offer several options as to the kind of trace produced. For example, there may be options to produce a statement-by-statement trace, or to trace just those statements that alter the flow of control, or to trace changes to the value of a specific variable.