When you're out hiking and you realize you've passed the same dead tree for the third time, ­and sundown is 20 minutes away, a dog looking for a game of tug-of-war might be your best chance at making it home. Search-and-rescue dogs are smart, agile and obedient, but their high "play drive" is what makes them look for a missing person through snow and rain, down steep rock walls and in crevices that would make a claustrophobic run screaming.

At its most basic, the job of a SAR dog has two components: Find the origin of a human scent and let the handler know where it is. In this article, we'll learn what SAR dogs do and how they do it, see what SAR training entails and find out what a real search-and-rescue mission is like.