The exit status is an integer that is passed out of a program depending on whether its execution was successful. In C, a successful termination returns 0 or EXIT_SUCCESS. An error should result in EXIT_FAILURE. Both are defined in stdlib.h.
We typically try to keep our standard exit integer to 0. Other integers may be used for different errors and we don’t want to be overlapping, which can throw us off. We can return 1 for errors we may encounter.
On UNIX-like systems, the underlying syscall called when returning from main is the exit_group() call.