What does the 'return 0;' statement in a program signify?

The statement 'return 0;' in a program typically indicates that the program has successfully completed its execution. In many programming languages, particularly C and C++, the main function returns an integer value to the operating system upon its completion. A return value of 0 is a convention that signifies success, while any non-zero value usually indicates an error or a different type of failure.

This system allows both the programmer and the executing environment to determine whether the program finished as expected. When a program ends with 'return 0;', it communicates to the calling process that everything ran as planned without any errors that would disrupt its normal termination. As such, this statement serves as an important mechanism for managing process completion status in programming.