The last time I looked at random walks, I used them to calculate the value of Pi for Pi Day. But what is a random walk, really? A mathematician will tell you that it's a stochastic process—a path defined by a series of random steps. It's a pretty abstract concept, but I want to show you how it can reveal something fundamental about life itself—the proteins that make up you and me and everything around us. So let's start with the simplest random walk, in one dimension.