When a pop() operation is called on an empty queue, what is the condition called?

When a pop() operation is called on an empty queue, the condition is typically called "underflow." Underflow occurs when there is an attempt to remove an element from a data structure (like a queue or stack) that is already empty. In the context of a queue, this means there are no elements to dequeue, and the operation cannot be successfully completed.

In programming, handling such conditions is important to avoid errors. Most queue implementations will return an error message or an indication that the queue is empty when an underflow situation arises, allowing the programmer to manage the situation properly, perhaps by checking if the queue is empty before attempting a pop() operation.