What does the 'return 0;' statement indicate in the main function of a C++ program?

The statement 'return 0;' in the main function of a C++ program signifies that the program has executed successfully. In C++, the value returned from the main function serves as an exit status code back to the operating system. By convention, returning 0 indicates that the program has run without any issues or errors, while a non-zero return value typically indicates the presence of some error or exceptional condition.

This convention provides a way for other programs or scripts that might call your program to determine whether it has finished its task successfully or if any problems arose during its execution. Therefore, recognizing 'return 0;' as an indication of successful completion is essential for structuring robust C++ applications.