High Quality Content by WIKIPEDIA articles! In physics, the Tsallis entropy is a generalization of the standard Boltzmann-Gibbs entropy. It was an extension put forward by Constantino Tsallis in 1988. It is defined as S_q(p) = {1 over q - 1} left( 1 - int (p(x))^q, dx right), or in the discrete case S_q(p) = {1 over q - 1} left( 1 - sum_x (p(x))^q right). In this case, p denotes the probability distribution of interest, and q is a real parameter. In the limit as q 1, the normal Boltzmann-Gibbs entropy is recovered. The parameter q is a measure of the non-extensitivity of the system of interest. There are continuous and discrete versions of this entropic measure.