In 1964 the author's mono graph "Differential- und Integral-Un-
gleichungen," with the subtitle "und ihre Anwendung bei Abschätzungs-
und Eindeutigkeitsproblemen" was published. The present volume grew out
of the response to the demand for an English translation of this book.
In the meantime the literature on differential and integral in-
equalities increased greatly. We have tried to incorporate new results
as far as possible. As a matter of fact, the Bibliography has been
almost doubled in size. The most substantial additions are in the field
of existence theory. In Chapter I we have included the basic theorems on
Volterra integral equations in Banach space (covering the case of
ordinary differential equations in Banach space). Corresponding theorems
on differential inequalities have been added in Chapter II. This was
done with a view to the new sections; dealing with the line method, in
the chapter on parabolic differential equations. Section 35 contains an
exposition of this method in connection with estimation and convergence.
An existence theory for the general nonlinear parabolic equation in one
space variable based on the line method is given in Section 36. This
theory is considered by the author as one of the most significant recent
applications of in- equality methods. We should mention that an
exposition of Krzyzanski's method for solving the Cauchy problem has
also been added. The numerous requests that the new edition include a
chapter on elliptic differential equations have been satisfied to some
extent.