The theory of random graphs studies typical properties of random graphs, those that hold with high probability for graphs drawn from a particular distribution. For example, we might ask for a given value of formula_11 and formula_12 what the probability is that formula_13 is connected. In studying such questions, researchers often concentrate on the asymptotic behavior of random graphs—the values that various probabilities converge to as formula_11 grows very large. Percolation theory characterizes the connectedness of random graphs, especially infinitely large ones.