Want to feel insignificant? Stop reading this review and take a second to contemplate 6.8 billion. It’s an extraordinarily vast, staggering sum, almost unfathomable. And yet, throughout the world, every day, 6.8 billion people laugh and cry, love and fight, experiencing the joys and heartbreaks that are fundamental to life, as their own stories are written. Last summer, YouTube put out a global call for user-generated submissions of home movies depicting life on July 24, 2010. Life in a Day, the resulting film (assembled by director Kevin MacDonald, with an assist from producer Ridley Scott), culled into an hour-and-a-half from 90,000 entrants, is an extended montage of select clips drawn from the submissions.