A sentinel loop is a special form of a while loop that uses a boolean condition called a sentinel. The loop runs until the sentinel is reached. In a sentinel loop a boolean statement needs to be initiated that states the condition that needs to be met for the loop to terminate. Inside the loop their needs to be a way to update the sentinel. An example of a sentinel loop would be a loop that runs until the user types "stop". Stop would be the sentinel and the code would be written so that the loop would run until the user types stop.