Both the formalism and many of the attendant ideas related to the random walk lie at the core of a significant fraction of contemporary research in statistical physics. In the language of physics the random walk can be described as a microscopic model for transport processes which have some element of randomness. The starting point of nearly all analyses of transport in disordered media is to be found in one or another type of random walk model. Mathematical formalism based on the theory of random walks is not only pervasive in a number of areas of physics, but also finds application in many areas of chemistry. The random walk has also been applied to the study of a number of biological phenomena.
Despite the obvious importance of random walks in these and other applications there are few books devoted to the subject. This is therefore a timely introduction to the subject which will be welcomed by students and more senior researchers who have had no prior contact with the field. The author has focussed on simpler aspects of the subject, focussing mainly on Markovian models, or models closely related to a Markovian formulation. Such models are exemplified by the continuous-time random walk which has both Markovian and non-Markovian aspects. Considerable emphasis has been placed on asymptotic properties of random walks because their universal properties are the ones that permit such a wide range of applications of the mathematical formalism. Attention is also given to an introductory account of Abelian and Tauberian theorems.
