The random walk is the trajectory that arises when an object moves in steps that are all the same length, but in random directions. The path of a molecule in a gas follows a random walk, with the step size determined by how far (on average) the molecule can travel before it collides with something and changes direction. The behavior of many diverse systems can be modeled as a random walk, including the path of an animal searching for food, fluctuating stock prices, and the diffusion of a drop of food coloring placed in a bowl of water.