Question: What is the Timer?
The term "timer" was first introduced in Episode 2x3, Orientation.
Answer: The timer is a group of numbers in the Swan Station. It starts at 108.00 minutes. When the timer gets down to four minutes, a "blip" type of alarm sounds and someone needs to enter the numbers into the computer. Once the numbers are correctly entered and the "execute" button pressed, the timer resets to 108.00.
In episode 2x14, One of Them, the timer reaches zero a split second before the execute button is pushed, and some symbols are shown in place of the numbers.
In a flashback, Desmond doesn't get the numbers input in time and symbols come up on the timer and the station shakes (Ep: 2x23, Live Together, Die Alone).
Later, Locke destroys the computer so that the numbers can't be input and the timer reaches zero. The symbols show on the timer and the station shakes and then implodes (Ep: 2x23, Live Together, Die Alone).
