The ephemerality sharpens viewers’ focus: Once received, a Snapchat count-down is a kind of time-bomb that demands an urgency of vision, a challenge to exhaust the meaning from the image before the clock runs out. Unlike a paper photo that fades slowly over the years, the temporary photo disappears suddenly. Given only a peek, you look hard.

-Nathan Jurgenson, Pics and It Didn’t Happen