This book surveys the most recent research in six key areas related to numerical solutions of differential equations. It covers guaranteed error bounds for ordinary differential equations; an introduction to computational methods for differential equations; numerical solution of differential-algebraic equations, boundary element methods; and perturbation theory for infinite dimensional dynamical systems. It draws together a method that is currently only available in journals, introducing the reader to important current research. This book is written at a level for graduate students and researchers in computational mathematics and in application areas in physics and engineering.