The arch of your foot is supposed to act like a spring—it absorbs impact, supports your weight and propels your body forward with every footstrike. Unless, of course, you're flat-footed.
Without that extra shock-absorbing spring, the impact of each step is transferred to the rest of the leg. The most common scenario for flat-footed runners is that they overpronate, causing the foot to land at a highly exaggerated angle that could lead to injury. To avoid that fate, runners with flat feet or low arches should look first for shoes with good arch support.
Start by picking a shoe from your favorite brand with medial posts—which is simply a jargon-y way of saying a harder, more durable foam (usually gray) that's found along the arch of the midsole—or raised arches built into the insole. From there, try to find a comfortable level of cushioning for you, from motion control down to minimalist shoes. Try on each one, if you have to, to find the right fit for your foot.
From there, you can try similar models from other manufacturers. In the end, be sure to try as many different shoes as possible until you find what's most comfortable for your foot.
The shoes in our slideshow, mostly stability and motion control models, are a few of the top shoes from 2013 for flat-footed runners.