This book has two-fold aims. In a first part it gives an introductory,
thorough and essentially self-contained treatment of the general theory
of two-parameter processes that has developed since around 1975. Apart
from two survey papers by Merzbach and Meyer it is the first text of
this kind. The second part presents the results of recent research by
the author on martingale theory and stochastic calculus for
two-parameter processes. Both the results and the methods of these two
chapters are almost entirely new, and are of particular interest. They
provide the fundamentals of a general stochastic analysis of
two-parameter processes including, in particular, so far inaccessible
jump phenomena. The typical rader is assumed to have some basic
knowledge of the general theory of one-parameter martingales. The book
should be accessible to probabilistically interested mathematicians who
a) wish to become acquainted with or have a complete treatment of the
main features of the general theory of two-parameter processes and
basics of their stochastic calculus, b) intend to learn about the most
recent developments in this area.