What do you mean by busy waiting? Expalin with example.

Definition:
Busy waiting is where a process checks repeatedly for a condition- it is "waiting" for the condition, but it is "busy" checking for it. This will make the process eat CPU (usually).

For example, let us consider the following example,

function stay_running_until_there_is_internet() {

    while(check_internet() == 0) {

        \\ wait

    }

}

Polling is sometimes necessary and sometimes a good idea; Busy Waiting is very rarely necessary and is almost always a bad idea.