Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In probability theory, percolation critical exponents are percolating systems have a parameter p which controls the occupancy of sites on bonds in the system. At a critical value pc, the mean cluster size goes to infinity and the percolation transition takes place. As one approaches pc, various quantities either diverge or go to a constant value by a power-law in p pc , and the exponent of that power-law is the critical exponent. While the exponent of that power-law is generally the same on both sides of the threshold, the coefficient of the "amplitude" is generally different, leading to an amplitude ratio.