LEDs indicate at a glance what the status of the circuit is at any given moment. Once the reset switch, SI, makes contact,
the timer remains in that state until the start switch, S2, is pressed. When either switch is activated, LED1 (ready) and the time indicator, LED2, keep track of the situation. Although not necessary, the two LEDs should be of different colors (for example, red for "ready" and green for "time").